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ELEMENTARY 

PHYSIOLOGY 
AND HYGIENE 



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SILVER, BURDETT Er COMPANY 



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Class 
Book 



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122. 



Copyright^ . 



COPYRIGHT DEPOSIT; 



AN 

ELEMENTARY PHYSIOLOGY 
AND HYGIENE 

FOR USE IN UPPER GRAMMAR GRADES 



BY 
H. W. COXX, Ph.D. 



PROFESSOR OF BIOLOGY IN WESLEYAN UNIVERSITY 



THE PUBLIC HEALTH AND THE CITIZEN 




SILVER, BURDETT AND COMPANY 

NEW YORK BOSTON CHICAGO 



4 



*v 



Copyright, 1903, 1906, 1910, 
By SILVER, BUEDETT AND COMPANY 



©CLA^73070 



PREFACE 

The aim of the author in writing the present work 
has been to furnish an elementary text-book in physi- 
ology and hygiene which should recognize some of the 
more important discoveries of recent years concerning 
matters pertaining to health, and which should also 
attempt to exemplify in the clearest way the inter- 
relation between physiology and hygiene. 

The primary object of the study of physiology in our 
schools is to inculcate an intelligent care of the body. 
^Vith this in view, matters of hygiene must in one 
sense take first place, although our understanding of 
hygiene must be based upon a knowledge of physi- 
ology. In the present work the study of the body, of 
its various parts and their functions, is given full and 
comprehensive treatment; at the same time lessons on 
hygiene are given as natural results of the principles 
of physiology and as closely related thereto. 

A knowledge of foods and their values and of the 
causes and distribution of contagious and other germ 
diseases is of vital importance to every boy and girl. 

The effect of alcohol upon the various functions of 
the body is treated throughout the book in direct rela- 
tion with the particular organs or functions concerned. 
The dangers connected with the use of alcohol will be 
found plainly indicated in accord with the results of the 
latest investigations in that department of science. 

3 



4 PREFACE 

The author desires to express his hearty acknowledg- 
ments to Superintendent W. P. Ferguson of Middle- 
town and Dr. George W. Fitz of Boston for their 
kindness in looking over the proofs of the work and 
giving him the benefit of their criticisms. He wishes 
also to express his obligations to Professor W. O. At- 
water, Professor William N. Bice, and Dr. F. G. Bene- 
dict of Wesleyan University, to Professor C. F. Hodge 
of Clark University, to the Kev. J. H. James, President 
of the Connecticut Temperance Union, and to Superin- 
tendent J. GL Edgerly of Fitchburg, Massachusetts, for 
their valuable suggestions. While acknowledging ob- 
ligations to these gentlemen, it is not implied that any 
of them can be held responsible for the method of treat- 
ment in the work or as necessarily indorsing it. 

In connection with this new edition the author de- 
sires to call particular attention to the new chapter on 
Preventable Diseases, and the enlarged discussions of 
the subjects of Public Hygiene and Emergencies. It 
is hoped that the presentation of these subjects will 
help to make the young citizen an intelligent and 
efficient member of the community in matters that 
pertain to the public health. 



CONTENTS 



Foods and Drinks 
Purposes of Food 
Kinds of Food 
Sources of Food 
Other Food Material 



PAGE 

11-36 



Alcohol 

Amount of Food Needed 

Comparative Food Values 



II. Digestion . 

The Mouth 

Food in the Mouth and 

Throat 
Food in the Stomach 
Food in the Intestines 



37-64 

Digestibility of Foods 
How the Food gets into 

the Blood 
Undigested Portions of 



the Food 



III. Food Habits and Cooking .... 
Proper Habits of Eating Purposes of Cooking 
The Habit of using Alco- Principles of Cooking 

hoi 

IV. Circulation 
The Blood 
What makes the Blood 

Flow 
Blood Vessels 
How the Blood Flows 

V. Respiration 

The Air Passages and the 

Lungs 
How Air is drawn into 

the Lungs 



65-79 



Methods of Cooking 



80-103 

How the Flow of Blood is 
Controlled 

Summary of the Circula- 
tion Process 



104-123 

What Breathing does for 

the Blood 
Ventilation 
How to restore Respiration 



6 CONTENTS 

CHAPTER PAGE 

VI. The Framework and Motion of the Body 124-152 

The Skeleton Joints 

The Bones The Muscles 

Cartilage 

VII. The Kidneys and the Skin and their Duties 153-171 

Waste Products The Skin 

The Kidneys Functions of the Skin 

VIII. The Care of the Skin . . . . . 172-179 
Bathing Burns 

Clothing Frostbites 

IX. Alcohol and Other Narcotics . . . 180-188 
Opium Alcohol 

Tobacco 

X. The Nervous System 189-197 

The Brain The Nerves 

The Spinal Cord 

XL The Nervous System in Action . . . 198-212 
Duties of the Nerves The Cerebellum and Cerebrum 

Duties of the Spinal Cord The Importance of Habits 
and Medulla The Care of the Mind 

XII. The Senses 213-236 

The Sense of Sight The Sense of Smell 

The Sense of Sound Skin Sensations 

The Sense of Taste 

XIII. Health and Disease 237-251 

Parasitic Diseases The Duty of preserving 

The Use of Alcohol Health 

XIV. Preventable Diseases 252-27G 

Germ Diseases Preventable Diseases of the Blood 
Source of Disease Germs Skin Eruptions 

Diseases of the Mouth and Preventable Diseases 

Respiratory Organs Immunity against Germ 

Diseases of the Digestive Diseases 
Organs 



CONTEXTS 



CHAPTER 








PAGE 


XV. 


A War for the 


Nation .... 


277-290 




Consumption not 


He- 


How to Combat Bactei 


:ia 




reditary. 




Alcohol and Consumption 




Consumption can 


be 


Precautions for Consump- 




Prevented 




tives 






Consumption can 


be 


Food and Exercise 






Cured 




Animal Tuberculosis 




XVI. 


Public Hygiene 
Boards of Health 
Water 




Foods 

Garbage and Sewage 


291-304 




Fresh Air 




Protection from Conta: 


oious 



Diseases 

XVII. What to do in Emergencies 

Various Diseases Sunstroke 

Accidents Poisons 

Bites of Insects and 
Snakes 



305-315 



XVII I. How to Develop our 

Breathing- 
Walking 

Exercises for Suppleness 
— Ease of Motion 



Bodies . . . 316-332 
Exercises to Develop Vari- 
ous Parts of the Body 
Games and Sports 
Alcohol and Athletics 



Glossary 333-311 

Index 342-349 



ILLUSTRATIONS 



FIG. PAGE 

1. Starch Grains 16 

2. Fat Cells 17 

3. A Small Bit of a Grain of Wheat ,.,... 21 

4. The Oat Plant 22 

5. A Small Bit of Potato 23 

6. Yeast Plant' . .27 

7. Sugar Solution undergoing Fermentation by Yeast . 28 

8. Showing the Proportion of Alcohol and Water in Beer, 

Wine, and Whisky . 29 

9. The Upper Teeth 39 

10. The Mouth 40 

11. A Diagram of the Side of the Face ..... 41 

12. A Section through the Head .;.... 44 

13. The Digestive Organs of the Abdomen . . , .47 

14. A Section of the Wall of the Stomach .... 48 

15. Showing the Location of the Digestive Organs . . 50 

16. A Bit of the Intestine 58 

17. A Bit of the Intestine 59 

18. A Single Villus 60 

19. A Simple Device for showing how Foods may pass 

through Membranes 61 

20. A Little Blood as it appears under a Microscope . . 81 

21. The Heart 83 

22. A. The Chief Arteries and Veins. B. Showing the 

Entrance of the Chief Veins into the Heart facing 84 

23. The Right Side of the Heart 84 

24. The Left Side of the Heart 84 

25. Capillaries 88 

26. Diagram showing General Circulation 89 

27. Showing Main Artery of the Arm . , , . ,91 

8 



ILLUSTRATIONS 



28. Showing Main Artery in the Leg 91 

29. Showing how to compress the Arm to stop Bleeding . ' 92 

30. Showing the Method of applying a Ligature . .93 

31. Showing the Clotting of Blood » 94 

32. Section of an Artery and a Vein 98 

33. The Lungs 107 

34. Air Sacs ■ 108 

35. The Air Sac of the Lungs .... facing 108 
36» Muscle Fibers facing 108 

37. Showing Chest with Lungs and Heart behind the Ribs . 109 

38. Showing Movement of the Diaphragm in Breathing . 110 

39. Showing Movement of the Ribs in Breathing . . .111 

40. Ventilation 119 

41. The Method of Moving the Arms to produce Artificial 

Breathing 121 

42. The Human Skeleton ... ... 125 

43. Two Vertebrae in Position 126 

44. The Human Skull ......... 127 

45. A Section of the Femur ....... 128 

46. The Cramped Foot 130 

47. The Uncramped Foot 130 

48. An Improperly Shaped Shoe . . . . . 131 

49. The Properly Shaped Shoe 131 

50. Two Vertebrae . . . . , . . .133 

51. The Bones forming the Knee Joint . 135 

52. The Knee Joint 136 

53. The Bones of the Shoulder Joint 138 

54. The Shoulder Joint 139 

55. Showing Method of Attachment of Biceps Muscle to 

move the Forearm 141 

56. Showing Muscles and Tendons of the Arm . . . 142 

57. A Bit of Muscle 143 

58. A Bit of Muscle 143 

59. The Surface Muscles of the Body 147 

60. The Kidneys 155 

61. A Section of a Bit of Skin . . . . .157 

62. A Hair . 159 

63. A Section through the Tip of the Finger . . . 161 



10 



ILLUSTRATIONS 



FIG. 

64. 

65. 

66. 
67. 
68. 
69. 
70. 
71. 
72. 
73. 
74. 
75. 

76. 

77. 
78. 
79. 
80, 

82. 
83. 
84, 
86, 
88. 



90. 

91. 

92. 

93. 

94. 

95, 

98. 

99, 

101. 

102, 

105, 

107, 

109. 



A Bit of Skin as it appears under a Microscope 

The Human Brain 

The Nervous System 

Two Pieces of the Spinal Cord 

A Nerve 

A Nerve Cell '. 

Showing Connection of Hand with Brain by a Nerve 
The Brain in Position . . . .... 

The Eye, viewed from in Front 

The Eye, viewed from the Side 

A Comparison of the Structure of a Camera and the Eye 
A Diagram representing a Section through the Human 

Eye 

The Ear 

The Tongue 

A Vertical Section of the Nose 
Bacteria that Produce Certain Diseases . 

81. Comparative Diagrams 253 

The Common House Fly . 

The Hook Worm 

85. Anopheles and Culex 

87. Stegomyia and the Flea 

The Rat .... 

Diagram comparing the Deaths due to Four Years 

Civil War and Four Years of Tuberculosis 
A Sleeping Veranda at a Consumptives' Home 
The Sun Parlor of a Large Hospital 
A Well Properly located .... 
An Unhealthful Location for a Well 
Diagram of Connections with City Sewers 
96, 97. A Bumble Bee, a Wasp, and a Honey Bee 
The Leaves of the Woodbine and Poison Ivy 
100. Illustrating Exercises 1 and 2 . 

Illustrating Exercise 4 . . 

103, 104. Illustrating Exercises 5, 7, and 8 

106. Illustrating Exercises 18 and 19 

108. Illustrating Exercises 20 and 21 

Hammer Throwing 



PAGE 

164 
190 
192 
193 
195 
196 
199 
206 
214 
216 
217 

218 
222 

227 
230 
240 
254 
262 
263 
264 
266 
2<37 

278 
283 
284 
293 
294 
29S 
308 
310 
323 
325 
326 
320 
330 
331 



PHYSIOLOGY AND HYGIENE 

CHAPTER I 

FOODS AND DRINKS 

Our bodies are in some respects like an engine 
that is constantly at work. As an engine is cold and 
powerless without fuel, so our bodies without food 
would starve and die. As the engine usually works 
smoothly and strongly, so the body, when we are in 
good health, is strong and active. But sometimes the 
body, like the engine, breaks down in part, and cannot 
do all its work. Then we say that we are ill. Smooth 
action of the engine means good health. When any- 
thing interferes with its working properly, sickness 
results. If the machine stops entirely, we say there is 
death. Physiology teaches us about the body, what 
the work of each part is; and Hygiene teaches us how we 
may treat the body wisely, just as the skillful engineer 
cares for his engine in the best possible way. 

PURPOSES OF FOOD 

When we speak of food, we ordinarily mean materials 
suitable for us to eat. In this chapter we shall include 
in the word "food," only the portion of the food 

11 



12 PHYSIOLOGY AND HYGIENE 

material that can be taken into the blood, and so can give 
nourishment to the body without injuring any of its 
parts, and not including that, which passes out as waste. 

In order that an engine, may be kept running, it is 
necessary, of course, that*coal or other fuel be regularly 
supplied, so that the engine may continue to have heat 
under its boilers, and power to run. But the coal 
could not keep the wheels revolving if an important 
part of the engine should break down. The care of 
the engine, then, includes also the repairing or re- 
placing of parts that break or wear out. In much 
the same way our bodies need not only heat and 
energy, but also the constant building and repair of 
parts which are used up from day to day. Our food 
supplies us with material for building and repair, as 
well as for heat and energy. 

Foods for Building and Repair. — When you say, 
" I have grown two inches since last year," you mean 
that your bones and muscles have increased in size a 
certain amount during the last twelve months. Even 
after we have reached our full height, certain parts of 
the body still continue to grow. The hair and finger 
nails need frequent cutting, and the skin is all the 
time wearing away. Although we cannot see so 
readily that the bones and muscles wear out and 
require constant repair, it is equally true. It is neces- 
sary, then, that our bodies receive in food some building 
material which can be used to increase the size of 
growing muscles and bones, and to replace those parts 
that are worn out. 



FOODS AND FOOD MATERIALS 13 

Foods for Fuel. — In addition to the material used 
for building and repair, our bodies need food that will 
serve as fuel, like the coal on the steamship, to supply 
heat, and power to use the muscles. Although we may- 
feel so cold that our bodies fairly ache, as we say, still, 
as long as our hearts beat, that is, as long as we live, our 
bodies are always warm. If you look at a thermom- 
eter, you will see that a certain point on the scale 
is marked "blood heat." This means that the point 
marked 98° is about the normal temperature of the blood. 
If the blood is cooler than this, we are ill; even a de- 
gree or two of additional heat in the body is fever. As 
we shall learn in a later chapter, our bodies are kept 
at the proper temperature by using up certain food 
materials, much as a stove or heater is warmed by the 
burning of coal. The flame which we see when wood 
or coal is burned is caused by the uniting of the fuel 
with a gas in the air which is called oxygen. In a 
similar way, but without flame, the heat-giving foods 
which we eat combine in our bodies with the oxygen 
which has been taken in with the air we breathe. 

KINDS OF FOOD 
The kinds of food which people eat appear to be 
numerous. As we study them carefully, however, we 
find that although our dinner table may hold a number 
of delicious things, the different articles of food are 
made up of a very few substances. Some of these 
substances, of which we shall learn more very soon, 
furnish our bodies with both building material and 
fuel, others chiefly with fuel. 



14 PHYSIOLOGY AND HYGIENE 

Let us now consider these special food substances 
which are contained in the things we eat. 

Foods used for both Fuel and Repair. Albumen. — If 
we break an egg carefully, we can separate the white 
from the yolk. This white, transparent, jellylike sub- 
stance is known as albumen, and is a valuable food 
substance. The white of the egg is one of the purest 
forms of albumen, but though we cannot see it so 
readily, albumen is found in meat, milk, and other 
articles of food. If you heat the white of the egg, it 
becomes solid, undergoing a change called coagulation. 

Myosin. — The lean part of meat after the gristle has 
been removed is another important food substance, and 
is called myosin. Uncooked myosin is soft and elas- 
tic ; but cooking coagulates it, just as boiling hardens 
the white of the egg. 

Gluten. — If we wrap a little flour in a piece of fine 
muslin and allow water to run through it, most of the 
flour will be washed away. A sticky, gummy, white 
mass will be left. This is gluten. 

Casein. — Milk contains a food substance called 
casein. If. we pour a little weak acid, like vinegar, 
into the milk, the latter curdles. The curd, or thick 
whitish substance, is casein. When pressed into cakes 
and dried in a certain way, it becomes cheese. 

These foods, albumen, myosin, gluten, and casein, build 
up the body, help to keep it in repair, and serve also as 
fuel. They are called proteids, or nitrogenous foods, 
and without them the body would starve. It must 
not be supposed, however, that eggs, meat, flour, and 



FOODS AND FOOD MATERIALS 15 

milk are the only proteid foods, since there is some 
proteid in almost all classes of foods. Peas, beans, 
lentils, and similar vegetables are very rich in pro- 
teids, and are for millions of people the cheapest and 
most convenient of proteid foods. 

Foods used chiefly for Fuel. — A man might have the 
muscles of a Samson, but if he were unable to lift 
anything with his sinewy arm, or to run upon his well- 
built legs, he would be of no more use to the world 
than a statue. To enable us to use our muscles we 
need more than the building and repairing foods; we 
must give our bodies something that will supply 
warmth and muscular power. The proteids or building 
foods may be used partly for this purpose, but we have 
in addition three important food substances that act 
mainly as fuels, — starch, sugar, and fats. They furnish 
us with heat and the power necessary for motion. 
Although our diet cannot be confined to either class, 
we really need a larger amount of the fuel foods than 
of the proteids. 

Starch. — Starch is found in certain of our vegetable 
foods, such as flour, oats y and potatoes. For use in 
the laundry and as stiffening for puddingb, the starch 
is separated from the other substances found in pota- 
toes and corn ; we then call it either laundry starch 
or corn starch. We must remember, however, that 
starch is really present in every potato, every kernel 
of corn, and every grain of wheat. We can easily see 
whether starch is contained in a fruit or a vegetable 
by touching it with a drop of water containing a little 



16 



PHYSIOLOGY AND HYGIENE 




iodine. 1 If there is starch in the vegetable, the spot 
touched will turn blue. The starch always appears 
in the form of very minute grains. Figure 1 shows 
starch grains as they look when seen through a power- 
ful microscope. 

We can cook our starch by putting a little into 
water and boiling it. The heat swells the grains of 
starch and the mass becomes a 
thick paste. 

Sugar. — Sugar, like starch, ii 
a fuel food, although in appear- 
ance and taste the two differ 
widely. There are several 
kinds, the so-called cane sugar, 
made from sugar cane, being one 
of the sweetest. Beet sugar, 
manufactured from the sugar 
beet, is also of excellent quality. Glucose or grape 
sugar, which is found in fruits and in corn, is less 
sweet than cane or beet sugar, but as it is more cheaply 
prepared for market, it is often used for adulterating 
other sugars. Milk contains a kind of sugar known 
as milk sugar. All sugars are of about equal value as 
foods, despite their different degrees of sweetness. 

We can readily observe a difference between sugar 
and starch by placing a little sugar in water and heat- 
ing gently, and then repeating the experiment with 
starch. The sugar quickly dissolves, while the starch 

1 A few drops of tincture of iodine in a teaspoonful of water 
sufficient for a number of tests. 



Fig. 1. — Starch Grains 

As seen through a 

microscope. 



FOODS AND FOOD MATERIALS 17 

does not, but, as we have already seen, swells if the heat 
is sufficient. 

Starch and sugar, though so different in some re- 
spects, are closely related and have much in gommon. 
Starch is changed to sugar in fruits as they ripen, in 
seeds and bulbs as they grow, and the same process 
takes place in our starchy foods as they are digested. 

Fats. — Fats are among the very best fuel foods. It 
is because of its excellent heat-giving qualities that 
the Eskimos eat so much of the blubber or fat of seals 
and other animals ; the fat enables them to endure the 
severity of their cold climate. Butter, tallow, lard, olive 
oil, and cottonseed oil are fats. Some of the fats used as 
foods, such as butter and lard, come from animals ; and 
others, such as olive and cottonseed oils, from the vege- 
table world. Several of the fats, like lard, are solid 
when they come from the market, becoming liquid 
only when subjected to heat ; others, like olive oil, 
are always liquid. 

Animal fat is made up f^Sf jJr^y/W 

of little drops, each in- 
closed in a sac. The sacs 

can be seen only with Connecwi { JH^^^^ffC 
the aid of a microscope. Htiue 

Figure 2 shows a group . Fig. 2. —Fat Cells. 

of fat cells as they thus ** they ^ in a pie ° e ° f meat 
v/ A «.w wiw c*o v±±k.j u* ^ under a microscope. 

appear ; the figure shows 

five fat drops in their sacs, in the form in which they 
are found in animal foods, such as a piece of beef- 
steak. We must remember, however, that when we 




18 PHYSIOLOGY AND HYGIENE 

look at animal fat it is solid and white because it is 
cold. In the living animal it is liquid, because of the 
heat of the body, and it is transparent. 

Melted fats or oils, when mixed with certain liquids, 
break up into very small drops, making the liquids 
look white. The millions of minute fat drops in milk 
aid in giving the liquid its white color. 

To test this, place a few drops of olive oil or castor 
oil and some water in a small bottle and shake rapidly. 
Then let it stand for an hour or so and note the change. 

Material for Bone Making. — As we shall see later, 
bones are made up of two widely different materials. 
Part of the bone, what is called the organic matter, is 
made up from the proteids which are so useful in build- 
ing up other parts of the body. The harder mineral 
matter of the bone is lime, which is contained in small 
quantities in such common foods as meat, bread, milk, 
and eggs. Thus our ordinary food furnishes us with 
all material needed for bone building. 

SOURCES OF FOODS 

Although the substances about which we have just 
been studying are the foods necessary to sustain life, we 
seldom eat any one of them singly or in a pure form. 
Take bread, for example. As usually made, it contains 
flour, milk, sugar, lard, and salt. The flour gives us 
starch and gluten, the milk casein and sugar, the lard 
fat. And so it is with almost everything we eat. 
Usually several food substances are to be found in 
each single article of diet. See tables, pages 33-35. 



FOODS AND FOOD MATERIALS 19 

Foods come both from animals and from plants. The 
principal animal foods are milk, meats, and eggs. 

Milk. — Milk is one of the cheapest and best of foods. 
We may be sure, as it is the natural food for babies, 
that it is easily digested and contains all the materials 
necessary for life, growth, and activity. The curd is 
the body-building food, and the cream, or fat, and the 
milk sugar are the force-producing foods. We should 
always remember that milk should be used as a food, 
and not to take the place of water as a drink to quench 
thirst. 

Milk should usually be the chief food for a child 
until his first teeth appear. When he becomes active 
and begins to walk, milk does not furnish enough 
force-producing material, and this must be obtained 
from starchy foods, such as bread, crackers, and other 
cereal foods. 

The fat or cream may be allowed to rise to the sur- 
face of the milk and can then be taken off and churned 
into butter. The skimmed milk remaining still holds 
most of the sugar and just as much of the building 
food as could be found before the cream was re- 
moved ; therefore it remains a valuable food. Skimmed 
milk contains a little less fuel substance than does 
new milk, but it is equally serviceable for body build- 
ing. It is so cheap that it is a valuable food for those 
who have but little money to spend. The curd, when 
separated from the rest of the milk, is pressed and 
dried to make cheese. Both cheese and outter are very 
useful foods. 



20 PHYSIOLOGY AND HYGIENE 

Danger in Milk. — Since milk is capable of holding 
and transmitting the germs of certain diseases, it is 
sometimes a source of danger. Typhoid fever, diph- 
theria, scarlet fever, and tuberculosis (consumption) 
are occasionally caused by impure milk. Much of the 
illness suffered by babies and little children in warm 
weather may be traced to milk which has been made 
impure by a lack of cleanliness about milkmen, cows, 
barns, milk-houses, or milk-cans. It is necessary that 
milk, and all utensils holding it, should be kept per- 
fectly clean. Some dealers send men to inspect the 
farms from which they obtain milk, to see that every- 
thing about the dairy is kept neat. 

To avoid these dangers, milk should be bought from 
a reliable dealer. It should be kept cold until used, 
and all dishes in which it is to stand should be washed 
with boiling water before the milk is put into them. 
It is wise also, especially in warm weather, to " scald " 
the milk which is to be used by young children or 
invalids. This removes much of the possibility of 
danger, and is very little trouble, as the milk needs 
only to be brought to the boiling point (but not boiled) 
and then cooled. Milk that has been boiled is not so 
wholesome as milk that has merely been "scalded." 

Meats. — Common meats consist of lean substance, 
or flesh, with some fat and considerable water. The 
flesh (myosin) is one of our most valuable body- 
building foods. So far as the amount of useful food 
is concerned, cheap meats are as nourishing as the 
more expensive cuts. A pound of round steak will 



FOODS AND FOOD MATERIALS 



21 



give us just as much good food as an equal quantity 
of porternouse steak. The extra money for high-priced 
meat is paid largely because these cuts are more tender 
than the cheaper parts and because the taste is in some 
respects better. 

Eggs. — Albumen and fats are the principal foods 
in eggs. When cooked but a little, whether boiled 
in the shell or dropped into hot water, eggs are health- 
ful and nourishing. Hard-boiled eggs are less easily 
digested, because the juices of the stomach do not act 
readily upon the tough, coagulated mass. When very 
thoroughly chewed, however, they are more readily 
digested. 

Plant Foods. — A large part of our food comes from 
plants. The 
most impor- 
tant of the 
plant foods 
are grains or 
cereals. The 
chief cereals 
eaten in this 
country are 
wheat, oats, 
rye, and corn 
(which are 
ground iuto 

flcur, graham meal, oatmeal, rye meal, and Indian meal), 
and rice. In the countries of eastern Asia rice is the 
chief cereal used for food. 




Fig. 



Starch Cells 

G/uten 
Cells 

3. — A Small Bit of a Grain of Wheat. 

Highly magnified. 



22 



PHYSIOLOGY AND HYGIENE 



All cereals contain a large proportion of starch, or 
fuel food, and a small amount of the building materials, 
such as gluten. Wheat is one of the best cereals, 
since it has more gluten (that is, more building food) 
than most of the others. Figure 3 shows a small piece 
of a grain of wheat as it appears under the micro- 
scope. Some of the cells, 
as indicated, are loaded 
with starch, and others, 
fewer in number, contain 
gluten. About one eighth 
of our wheat flour is glu- 
ten. Oats (Fig. 4) are 
even better food than 
wheat, containing, as they 
do, a still larger propor- 
tion of gluten. Rice fur- 
nishes less building food 
than wheat, but more fuel 
food (starch). Corn con- 
tains also considerable fat. 
All of these cereals are 
thus excellent foods. They give us more fuel than 
meat and eggs, but less of the proteids or building foods. 
Wheat bread supplies a good proportion of the necessary 
materials for fuel and repair. A person could keep from 
starvation on a diet of bread and butter alone, but a 
variety of foods is always desirable. Meat and cheese go 
well with cereals, since they furnish the proteid and fat 
elements lacking in the grains. 




Fig. 4. — Thb Oat Plant. 



FOODS AND FOOD MATERIALS 



23 



Beans and Peas. — As beans, peas, lentils, and peanuts 
contain large quantities of starch and proteids, they are 
especially nourishing foods. More than one fifth of the 
substance of the bean is proteid, a larger proportion 
than is contained even in meat. Although they are 
not so easily digested as meat, they serve as an excel- 
lent substitute, and they are cheaper. 

Fruits and Vegetables. — Although most fruits and 
vegetables contain little of the real food substances, 
they stimulate the appetite and thus give relish to the 
more substantial foods. They are composed largely of 
water, with a small amount of starch or sugar, flavoring 
matter which makes them pleasant to the taste, and also 
certain salts which aid digestion. 

Some of them, however, such as potatoes, beets, 
bananas, cocoanuts, and nuts, contain sufficient starch, 
proteid, sugar, or fat 
to be valuable as 
foods. Indeed, vege- 
tables and acid fruits 
seem to be needed by 
the body, as sailors 
or explorers, when 
deprived of them, 
suffer from scurvy 
and other diseases. 

Figure 5 represents 
a bit of potato magnified, showing the grains of starch. 
As the potato consists so largely of starch, it is a fuel 
food, and we should eat with it meat, milk, cheese, or 




? ~~ Starch 

Fig. 5. — A Small Bit of Potato. 

Highly magnified. Showing cells filled 
with grains of starch. 



24 PHYSIOLOGY AND HYGIENE 

some other food which will supply proteids for the 
building material which the potato lacks. 

We may eat freely of fruits if they are ripe and per- 
fectly sound, but unripe and overripe fruits are un- 
wholesome and injurious to health. 

OTHER MATERIALS NOT TRUE FOODS 

There are certain other substances which we eat or 
drink that are not true foods. Some of them are neces- 
sary to life, some of them are of use, others may be 
harmful. Let us see what some of these are. 

Water. — The shipwrecked sailor who is cast ashore 
on a rocky island or drifts about in an open boat can 
live for many days without food, but without water he 
soon becomes almost crazed with thirst, and in a 
very few days he dies. Our blood, muscles, and vital 
organs all contain water. Without this necessary fluid, 
the foods eaten could not be dissolved and thus made 
ready for transformation into blood and muscle. 

The various other drinks, such as milk, soda water, 
tea, and coffee, allay thirst only because of the water 
they contain, and none of them is equal to water itself for 
this purpose. If we quench our thirst with water only, 
we are not so likely to drink too much as we are when 
we attempt to satisfy ourselves with liquids containing 
other material. When we drink something that has 
an especially pleasing taste, the pleasure of taste may 
lead us to drink more than is wise. 

Cool water is one of the most refreshing of drinks on 
a hot day, but extremely cold water, if taken in large 



FOODS AND FOOD MATERIALS 25 

quantities when the body is overheated, may produce a 
shock which is harmful. Ice water or other cold water 
should be drunk very slowly. After violent exercise in 
the hot sun, it is wise to wait for a few minutes before 
drinking cold water. 

Impurities in Water. — It is not easy to find abso- 
lutely pure water. Some of the impurities in drinking 
water are harmless ; others are very injurious. Water 
sometimes contains certain minerals which it gets from 
the earth. These make the water "hard"; but though 
hard water sometimes produces slight bowel troubles, it 
is not especially harmful. 

The most dangerous impurities in water are minute 
living plants called bacteria. Some of these, as we shall 
notice in a later chapter, may produce disease, if they 
are taken into the body. One kind of bacteria, occa- 
sionally found in drinking water, gives rise to typhoid 
fever. It is impossible to judge either by the appear- 
ance or by the taste, whether water does or does not con- 
tain injurious bacteria. It may be perfectly clear and 
of the finest taste, and yet be unsafe to drink. 

Spring water is almost always pure, if the spring is 
deep and a good distance from any foul place, such as 
an open drain or a barnyard. The lakes and reservoirs 
from which cities obtain water are usually kept in good 
condition by the authorities ; if at any time the water 
becomes unfit to drink, people are advised to boil it. 
Wells, particularly if they are on a lower level than the 
houses or barns for which they supply water, are likely 
to contain injurious bacteria. These may either pass 



26 PHYSIOLOGY AND HYGIENE 

down through the soil or drain into the wells from the 
surface. River water is usually unfit to drink, especially 
if there are towns or cities on the banks that allow 
sewage to pour into the stream. Such water can be 
made healthful only by boiling. The dangerous bac- 
teria are destroyed by heat. When typhoid fever pre- 
vails, it is always a wise precaution to boil the drinking 
water. 

Mineral Substances. — Several mineral substances, 
called salts, are needed by the body in small amounts. 
Lime is required to make bone. We eat common salt 
with most of our food. Although salt neither builds up 
the body nor supplies fuel, it is absolutely necessary for 
health. Cattle will eat the grass grown on salt marshes, 
in spite of its coarseness, because they like the salty 
taste. Our ordinary food contains sufficient lime for 
bone material, as well as whatever other salts, aside 
from common salt, the body requires. 

Flavors. — While we do not partake of food simply 
because we enjoy eating, still the different articles of 
diet give us a certain pleasure because of their various 
flavors, and indeed some flavor to our foods is neces- 
sary to enable us properly to digest them. The taste 
of puddings, cakes, pies, and similar dishes is due 
largely to certain substances added to give a desired 
flavor. The most common of these flavorings are 
lemon, vanilla, and spices. Tea and coffee are liked 
partly because of their pleasant taste, partly because 
of their slight stimulating effect. Young people are 
better off without them, and taken in excess they are 



FOODS AXD FOOD MAlERIALS 27 

injurious to the nerves and the digestion of every one. 

Chocolate, in addition to having a fine flavor, contains 

real food. 

ALCOHOL 

Alcohol is a clear, transparent liquid, in appearance 
resembling water, but very different from water in its 
nature and effects. Although alcohol is found in 
smaller or larger quantities in various materials used 
for drinking purposes, it will neither quench thirst nor 
take the place of water in the body. Pure alcohol has 
a strong odor and an unpleasant taste. 

Although alcohol and water appear so. much alike, 
we can test the difference : 1. By smelling them — 
water is odorless, while alcohol has a pungent odor. 
2. By pouring a few drops 
of alcohol and water into 
saucers and applying a 
lighted match — the alco- 
hol burns. 3. By putting 
salt into water and also 

into alcohol— upon being FlG ' 6 -~ Y ^ 8T P ^ NT - 

Highly magnified, 
shaken gently, the salt 

dissolves in the water, while in the alcohol it remains 
undissolved. Similar results are obtained if we sub- 
stitute sugar for salt. 

How Alcohol is made. — Alcohol is made from sugar 
by a process called fermentation. The fermentation is 
brought about by a minute plant called yeast, to be 
seen only with the aid of a microscope. The common 
yeast which may be purchased at the grocery store con- 




28 



PHYSIOLOGY AND HYGIENE 



sists of many hundreds of thousands of these tiny plants 
(Fig. 6). If a bit of yeast is placed in a sirup made of 
water and sugar or molasses, the yeast grows, feeding 
on the sugar and very decidedly chang- 
ing in its nature. Bubbles of gas rise 
through the liquid in which the yeast 
is growing (Fig. 7). Besides this' gas 
there is produced at the same time a 
certain amount of alcohol which re- 
mains in the liquid. When the sirup 
has become entirely fermented, the 
sugar has disappeared and alcohol has 
taken its place. 

It is not always necessary to add 
yeast in order to start fermentation. 
Grape juice is changed into wine and 

any 



Sugar 
Solution 



.Carbonic 

Dioxide- apple juice into cider without 



Gas 



Alcohol 
'left in 
Solution 



Yeast 



yeast being put into them. But in 

these cases a ferment gets into the 

juice from the air. These air ferments 

are in reality almost the same thing 

as the yeast from the store. Like 

yeast they are tiny plants, so small and 

light that they are blown about in the 

air, and are soon ready to act upon 

sugary liquids if they fall into them. 

Fermented and Distilled Liquors. — Many kinds of 

drinks are made by fermenting sweet liquids obtained 

from the juices of fruits, such as grapes and apples. 

Other drinks are made from corn, barley, and various 



Fig. 7. — Sugar 
solution undergo- 
ing fermentation 
by yeast. 



FOODS AND FOOD MATERIALS 



29 



grains by sprouting the grain, and thereby changing 
its starch to sugar, which is then soaked out with 
water. These sweet liquids are caused to ferment by 
the action of yeast, either added in a form similar to 
baker's yeast or carried into the liquids from the sur- 
face of the crushed fruits or from the air. The com- 
mon drinks made by fermenting sweet liquids are beer, 
ale, wine, and cider. All of these contain alcohol as 
soon as they begin to ferment. It is the alcohol in 




Wine Whisky 

Fig. 8. — Showing the proportion of alcohol and water in 
beer, wine, and whisky. 



these drinks that makes them harmful. The drinks 
that contain alcohol are usually called liquors. Those 
obtained by fermentation are called fermented liquors. 
One danger of their use is that they cultivate an appe- 
tite for stronger beverages. The amount of alcohol 
which they contain ranges from one fiftieth to one fifth 
of the total volume of the liquor. The rest of the 
material is principally water (Fig. 8). 

Certain drinks called distilled liquors are made from 
fermented mixtures. By the process known as distill- 



30 PHYSIOLOGY AND HYGIENE 

ing, a part of the water is taken away, thus leaving 
a larger proportion of alcohol in the mixture. The 
strength of the liquor depends, of course, upon the 
amount of alcohol which remains. The proportion of 
alcohol in the distilled liquors used as drinks varies 
from one quarter to one half. The rest of the material, 
which is chiefly water with a little flavoring matter, 
contains nothing useful except the water itself. The 
distilled liquors include rum, whisky, gin, and brandy. 
Because of their large proportion of alcohol, such 
drinks are very harmful. A small amount of whisky 
will intoxicate much more quickly than a large amount 
of beer or ale. 

There is nothing in either fermented or distilled 
liquors that makes them necessary to any person in 
sound health. The boy or girl who wishes to be as 
vigorous, as useful, and as successful as possible should 
let them alone. 

Why People drink Alcohol. — Although when taken 
in very small quantities alcohol acts as a fuel, its value 
in this respect is practically nothing. 1 A few cents' 
worth of bread will furnish more heat and muscular 
energy than a much larger sum of money spent for any 
form of alcoholic drink. Why, then, do people use 
alcoholic drinks ? 

Some use them under the mistaken idea that they 
give muscular power and make us stronger. They cer- 

1 Although alcohol does thus act as a fuel, we should not for this 
reason class it with the fuel foods, like starches and sugars, since its 
general effect is to harm rather than to benefit the body. 



FOODS AND FOOD MATERIALS 31 

tainly do not make us stronger ; their tendency is rather 
to make us weaker, and they do this very decidedly if 
any considerable amount is used. 

Sometimes they are used to quench thirst. But it is 
only the water they contain that quenches thirst, and 
water alone will do much better. Indeed, the alcoholic 
drinks tend to excite the thirst instead of quenching it, 
so that people wish soon to drink again. 

Some people enjoy the taste, although pure alcohol 
is unpleasant to the taste, and most beers and wines 
are disagreeable at first to the majority of people. 
Then there are those who enjoy the excitement which 
the alcohol produces, a dangerous enjoyment, since it 
may lead them to do foolish or wrong things. Some 
who have betxrme accustomed to using alcoholic drinks 
find it difficult to overcome the habit. Here is one 
of the great dangers in using alcoholic liquors. All 
such drinks are apt to create an appetite for more and 
more alcohol. Many people who seem to be strong 
and capable of resisting the appetite, are finally mas- 
tered by it. No one is so safe from this danger as he 
who never begins to use alcoholic drinks. 

Intelligent people do not usually drink alcohol be- 
cause they consider it valuable as a food, and if they 
do, it is a mistaken idea. They drink it because they 
like the taste or the exhilaration it produces, or be- 
cause they cannot overcome the appetite for it. 



32 PHYSIOLOGY AND HYGIENE 

AMOUNT OF FOOD NEEDED 

How much food we should eat is a question not easy 
to answer. The amount depends somewhat upon a 
person's occupation. If a locomotive is running fast, 
it needs more fuel than if it moves more slowly, and 
when it stops, it requires only sufficient coal to keep 
the fire burning. So long as we live, our bodies never 
entirely cease action, for the heart always continues to 
beat ; but at certain times we are more active than at 
others, and when we are hard at work, more food is 
required than when we rest. A poorly fed person can- 
not do hard work. If a man, from a false idea of econ- 
omy, subsists largely upon starchy foods, like potatoes 
and rice, he will be unable to do as much hard work 
as his neighbor whose diet contains more of the muscle- 
building materials. The man of small income should 
spend more of his money on beans or cheese, or per- 
haps on skimmed milk, as these will aid in supplying 
strength for muscular work. 

The using of the body substance for muscular 
strength can be tested with the aid of scales. If a boy 
be weighed carefully before taking active exercise for 
an hour or two, and again after the exercise, the scales 
will show a difference in his weight. If the weighing 
is accurate and the boy has taken neither food nor 
water between the two weighings, the scales show just 
how much of the body substance has been used up 
during the muscular action, and consequently how 
much food and water are required to replace the loss. 



FOODS AND FOOD MATERIALS 



33 



COMPARATIVE FOOD VALUES 

The following table shows the food values which can 
be obtained for ten cents : — 

COMPARATIVE COST OF DIFFERENT FOOD MATERIALS 
AT AVERAGE PRICES. 





Price 

per 

pound 


Cost of 

1 pound 

pro- 

teids x 


Amounts for ten cents 


Kind of Food Material 


Total 
weight 
of food 
material 


Proteid 


Fat 


Starch 




Cents 


Dollars 


Pounds 


Pounds 


Pounds 


Pounds 


Beef, sirloin 


25 


1.60 


0.40 


0.06 


0.06 


- 


Beef, round 


16 


.87 


.63 


.11 


.08 


- 


Mutton 


16 


1.10 


.63 


.09 


.09 


- 


Pork 


18 


1.30 


.56 


.08 


.18 


- 


Pork-fat, salt .... 


12 


6.67 


.83 


.02 


.68 


- 


Butter 


25 


25.00 


.40 


- 


.32 


- 


Eggs, 24^ a doz. . . . 


16 


1.39 


.63 


.07 


.06 


- 


Cheese 


16 


.64 


.63 


.16 


.20 


.02 


Milk, 6? a qt 


3 


.94 


3.33 


.11 


.13 


.17 


Wheat flour 


3 


.31 


3.33 


.32 


.03 


2.45 


Corn meal, granular . . 


H 


.32 


4.00 


.31 


.07 


2.96 


Wheat breakfast food . . 


n 


.73 


1.33 


.13 


.02 


.98 


Oatmeal 


4 


.29 


2.50 


.34 


.16 


1.66 


Rice 


8 


1.18 


1.25 


.08 


- 


.97 


Wheat bread 


5 


.64 


2.00 


.16 


.02 


1.04 


iieans, white dried . . 


5 


.29 


2.00 


.35 


.03 


1.16 


Corn, canned .... 


10 


4.21 


1.00 


.02 


.01 


.18 


Potatoes, 60 f a bush. . . 


1 


.67 


10.00 


.15 


.01 


1.40 



1 The cost of one pound of proteids means the cost of enough of the 
given material to furnish one pound of proteids, without regard to the 
amounts of other food substances present. 



34 



PHYSIOLOGY AND HYGIENE 




Proteids 



Fats 



Carbo- 
hydrates 



This table shows the comparative amount of the dif- 
ferent food materials which can be purchased for ten 
cents. It shows that beans give the most proteid for 
the money and oysters the least. 



FOODS ASD FOOD MATERIALS 



35 




Proteids Fats Mineral Carbo- WaUr Refuse 
Matters hydrates 



This table shows the amount of the different food 
materials contained in the different foods. From this 
it will be seen that cheese is the most nutritious food. 
Beef is also very nutritious, but its high price makes it 
an expensive food, as is shown by the table on page 34. 



PHYSIOLOGY AND HYGIENE 



QUESTIONS 

1. For what purposes do we need food ? 

2. What are the two classes of foods? 

3. In what respect is meat a valuable food ? 

4. Why are beans especially useful as foods? 

5. If we drink skimmed milk, what food will go well with it ? 

6. Of what use to the body are starch, sugars, and fats? 

7. With what does albumen furnish the body ? ' 

8. Why is milk made more healthful by boiling ? 

9. Why do people buy porterhouse instead of round steak ? 

10. What food substances do we get from cereals? 

11. Why are potatoes so widely used as foods? 

12. Which would be the best meal : one made up of potatoes 
and rice, or one of potatoes and beans ? 

13. Why are not potatoes alone a good diet? What kind of 
food should we eat with them ? 

14. What is the chief use of fruits and vegetables ? 

15. Why do we need to drink water ? 

16. How can impure water be made fit for drinking? 

17. What does alcohol look like ? How is it made ? 

18. Why should people abstain from the use of alcoholic 
drinks ? 

19. Why do people use alcoholic drinks? 

20. What food do we get from cheese ? What does this food 
do for the body ? 

21. If you had one dollar to spend for a meal for four persons, 
what would you buy to make the most useful meal? (Consult 
tables on pp. 33-35.) 



CHAPTER II 

DIGESTION 

Before the bread and butter which we eat for 
breakfast becomes the blood and later the muscle of 
our body it meets with a number of changes. The 
process by which the food taken into the body is 
changed so that it can be absorbed into the blood, and 
thus be used for growth, repair, and warmth, is called 
digestion. Certain organs of our body have charge of 
this work and are called the digestive organs. 

THE MOUTH 

The food is received into the mouth, where the 
first step is taken in preparing it to enter the blood. 
The mouth is a large cavity with the cheeks for its 
sides, the tongue for a floor, and the palate for a roof. 
The front part of the palate is a hard, flat bone. The 
back part is a soft membrane, with a little finger-like 
piece called the uvula hanging from the middle and 
reaching almost to the tongue. (See Fig. 10.) 

The Teeth. — Around the sides and front of the 
mouth are two rows of teeth fastened securely in 
sockets in the jawbones. The front teeth have sharp 
edges for cutting or biting food, while those farther back 

37 



38 PHYSIOLOGY AND HYGIENE 

in the mouth have broader surfaces and are used for 
grinding or chewing the food into a fine mass. Each 
tooth consists of a crown, the part we see as we look 
into the mouth; a neck, which is surrounded by the 
gums; and a root, which fits into the socket in the jaw- 
bone. Each tooth has a tiny blood vessel entering 
through its root, and is also supplied with a nerve. 
When the nerve is exposed to the air as a result of 
decay, the tooth may ache. The crown of the tooth is 
covered with enamel, the hardest substance in the body. 

Growth of the Teeth. — In the course of life we have two 
sets of teeth. The first, or temporary teeth, begin to grow 
when the child is five or six months old, and they con- 
tinue to appear, one after another, for about three years. 
The temporary teeth are twenty in number. When 
the child is about six years of age, the second, or perma- 
nent teeth, begin to push their way through the gums ; 
the milk teeth are gradually loosened as the others push 
their way out. The first of the permanent teeth, called 
the " six -year molars," come so early that they are often 
mistaken for the last of the milk teeth. The permanent 
teeth are thirty-two in number. 

Figure 9 shows the permanent teeth. Their arrange- 
ment, as can be readily seen from the figure, is as 
follows, beginning at the middle of the upper set: two 
incisors, one canine, two bicuspids, and three molars. 
The other side of the upper row is similarly arranged, 
and the lower jaw holds sixteen teeth to match these, 
with names corresponding. Notice the sharp edges of 
the front teeth and the broad grinding surfaces of the 



DIGESTION 



39 



double teeth farther back; also the six-year molars. 
If you shut your teeth tightly together, you will appre- 
ciate how well the upper and lower teeth match. The 

edges of the upper 

.Incisors 
jZanbc 
^>3/'cusp/<h 




" Motor 
^Motors 



Fig. 9. — The Upper Teeth. 



front teeth slip 

over those of the 

corresponding 

lower teeth, so 

that the food may 

be bitten off as if 

cut by scissors. 

The projections of 1 

the upper back 

teeth are opposite 

the hollows of the corresponding lower ones, so that 

the food may be ground fine without difficulty. 

Care of the Teeth. — The teeth, when once they are 
fully grown, will never repair themselves. If j. bone 
of the arm is broken, the two edges can be set in the 
proper position, and the bone will knit, or grew to- 
gether again. If, on the other hand, a tooth is broken 
off or worn out, it will never repair itself. Teeth are 
liable to decay. The outside of the tooth, che enamel, 
is hard, but the inside is comparatively soft. As 
long as the enamel is in perfect condition, the tooth 
will remain sound, but if there is a crack in the 
enamel, decay is likely to start at the crack and enter 
the soft part inside. The tooth then decays rapidly 
until it is ruined. Even a very small hole in the 
enamel may result in a large cavity in the softer sub- 



40 



PHYSIOLOGY AND HYGIENE 



stance within. We should never pick the teeth with 
anything hard, such as needles or pins, because these 
are liable to scratch, and so crack, the enamel. Foi 
the same reason we should not crack nuts or other 
hard substances with the teeth. It is also harmful to 
the teeth to take extremely hot and cold foods or 
drinks in close succession. 

Particles of food lodged between the teeth become 
decayed and help to decay the teeth in turn. It is 
well, therefore, to brush the teeth after each meal, and 
also at night, so as to remove any bits of food that 
might do injury if allowed to remain. To keep the 
teeth healthy and sound, it is necessary, in addition 

to brushing 
them, to re- 
move, with a 
soft toothpick 
or thread, all 
bits of food 
which cling to 
them. When 
a tooth begins 
to decay, it 
should be at- 
tended to at 
once by a den- 
tist ; for if 

the small cavities are promptly filled, the tooth may 
perhaps be preserved for years, and much pain and 
expense be saved. 



Uvula 

Pillars or 

fauces •• 

7cvw//— .-. 




Eig. 10, — The Mouth. 
Showing the opening into the throat. 



DIGESTION 



41 



Figure 10 shows the open mouth as it appears when 
we look within. Notice the palate and the uvula. 
By placing the tip of the tongue on the roof of the 
mouth just inside the upper teeth and drawing the 
tongue slowly backward over the roof of the mouth, 
we can discover the difference between the hard and 
soft portions of the palate. 

Salivary Glands. — If some one says the word "lemon," 
our mouths are apt 
to water, as we think 
how sour the juice 
of the lemon is. The 
fluid which moistens 
the mouth, and 
whose flow is thus 
increased by the aid 
of the imagination, 
comes from the 
organs known as the 
salivary glands. The 
liquid produced is 
called saliva. There 
are three pairs of 
salivary glands. 
Those who have had 
the mumps can locate 

one of these pairs of glands without difficulty. These 
are the parotid glands, which are inflamed and swollen 
in that painful disease. They are situated just below 
and a little in front of the ears. There are two sali- 




Glands 



Fig. 11. — A Diagram of the Side of 
the Face. 

Showing the position of the salivary- 
glands and their ducts. 



42 PHYSIOLOGY AND HYGIENE 

vary glands under the lower jaw and two more beneath 
the tongue. All these glands are connected with the 
mouth by little tubes, called ducts, which carry the 
saliva from the glands into the mouth. The saliva 
is poured out of the tubes whenever it is needed. 
Although the salivary glands are constantly sending 
out enough saliva to keep the mouth moist, the act of 
chewing stimulates the action of the glands so that the 
amount is largely increased. 

Figure 11 shows the salivary glands on one side of 
the face, also the ducts that connect them with the 
mouth. 

FOOD IN THE MOUTH AND THROAT 

Need of Mastication. — After we have taken a bite of 
bread and butter, the first step towards its digestion is 
chewing or mastication. We chew our food to break 
it into small pieces so that the saliva may become 
thoroughly mixed with the food, and also that the di- 
gestive juices may afterwards do their work easily. 
The digestive juices in the stomach can act only on the 
outside of each piece of meat, and therefore the smaller 
the pieces, the shorter the time required to digest them. 

Many a person suffers from dyspepsia as a result of 
the foolish habit of swallowing his food partly chewed. 
Rapid eating is injurious, since it forces the stomach 
t@ do work that belongs to the teeth. Very solid foods, 
like nuts or hard-boiled eggs, can be digested properly 
only after they are thoroughly chewed. Some foods, 
such as oatmeal and mushes of different kinds, do not 



DIGESTION 43 

need much mastication, but solid food should not be 
swallowed until it is ground into a fine pulp. 

Use of Saliva. — While the food is being chewed it 
is moistened by the saliva that is poured into the mouth. 
The saliva serves two different purposes. 

1. Saliva moistens the food and the mouth. — If the 
mouth becomes dry, for any reason, we are very uncom- 
fortable, and even talking is difficult. Sometimes, if we 
are frightened, the glands stop producing saliva entirely, 
and as a result we find it difficult to swallow. How 
impossible it is to swallow food that is not thoroughly 
moist may be comprehended by eating a cracker. 

2. Saliva begins the process of digestion. — The water 
in the saliva dissolves some of the foods, like sugar, 
but this is not digestion proper. If, however, we 
chew a bit of bread for a few minutes, we find that 
it becomes a trifle sweet. The saliva changes the starch 
into sugar. The change begins as soon as the food is 
mixed with the saliva. It is the beginning of real 
digestion, although ordinarily the starch does not remain 
in the mouth long enough for much of it to be thus 
acted upon. If the food is acid (sour), as when it is 
mixed with vinegar, no change takes place in the mouth. 

The amount of saliva in the mouth may be increased 
by chewing gum. In the case of an athlete who wishes 
to keep his mouth moist during exercise, gum chewing 
may be useful. Under ordinary circumstances, how- 
ever, not only is the habit vulgar and impolite to the 
people about us, but the constantly stimulated action 
of the salivary glands is probably injurious. 



44 



PHYSIOLOGY AND HYGIENE 



Tonsils. — At the back of the mouth, as may be seen 
in Figure 10, there is a large opening leading to the 
throat. As soon as the food is chewed and moistened 
it is pushed back by the tongue through this opening. 
At each side of the opening may be seen a small 

rounded body 
called a tonsil. 
Sometimes 
when a per- 
son has taken 
cold, the ton- 
sils become 
swollen, and a 
kind of sore 
throat called 
tonsilitis re- 
sults. It is 
not known 
whether the 
tonsils have 
a special use 
or not. 

The Throat. 
— A cavity, 
called the 
throat, is situ- 
ated just back of the mouth. Into this the food passes 
after being chewed. The upper part of the throat 
opens into the nasal cavity, and from there, by way of 
the nostrils, to the exterior. Thus both the mouth 




Fig. 12. — A Section through the Head. 
Showing the relation of mouth, throat, etc. 



DIGESTION 45 

and the nostrils are connected directly with the throat. 
Figure 12 shows this relation. 

Two large tubes open downward from the throat. 
One, the gullet or oesophagus, extends to the stomach ; 
the other, the windpipe or trachea, connects with the 
lungs. The windpipe is placed in front of the oesopha- 
gus, and it opens at the top, so that the air we 
breathe may pass into it readily. The opening is the 
glottis. If a particle of food drops into the windpipe, 
it causes violent coughing and sometimes choking. 
To keep food from entering the windpipe as it passes 
over the entrance on the way to the gullet, the wind- 
pipe is provided with an elastic lid, somewhat like soft 
India rubber, which rests upon the opening. 

When we are breathing, this lid, which is called the 
epiglottis, is lifted as in the illustration (Fig. 12); but 
as food passes from the mouth, the lid closes for the 
moment so as completely to cover the opening into the 
windpipe and allow the food to slip safely over. As 
soon as the food has passed, the lid flies up again, and 
the windpipe is open once more, ready for its regular 
work of carrying air to the lungs. 

If we talk or laugh while our mouths are full of food, 
or while we are drinking, a bit of the food or water is 
liable to "go down the wrong way" ; that is, we may 
have the epiglottis open for a breath just at the moment 
the food or water ought to pass over to the oesophagus. 
Some of it then drops into the windpipe instead of slip- 
ping over the top, and violent coughing results, until 
the foreign matter is coughed out. 



46 PHYSIOLOGY AND HYGIENE 

Figure 12 shows a section of the head, indicating the 
shape of the throat and the openings into the mouth and 
nose, with the location of the windpipe and oesophagus. 
Notice the epiglottis at the top of the windpipe. 

Sore Throat. — Any soreness of the tonsils, the palate, 
or the throat makes swallowing painful, and we say we 
have a sore throat. Sore throat, especially in the case 
of children, should receive immediate attention. If a 
child feels any soreness when swallowing, his throat 
should be examined, and if there are whitish spots on 
the palate or the tonsils, a physician should be called 
at once, as the trouble may be serious. 

Swallowing. — After the food reaches the throat it is 
rapidly swallowed. While food remains in the mouth 
we can control it, but the moment it enters the oesopha- 
gus it has passed beyond our control. If we should 
then discover that it was poison, we should be obliged to 
keep on swallowing just the same. The food is pushed 
through the oesophagus into the stomach by the muscles 
of the throat and oesophagus. It does not simply fall, 
but it is actually forced down. A person can swallow 
water even when he is standing on his head, and a horse, 
when he drinks, of course swallows the water upward. 

FOOD IN THE STOMACH 
The Stomach. — A few seconds after the food has 
entered the oesophagus it passes into a large cavity called 
the stomach (see Figs. 13 and 15). This is a chamber 
similar to a gourd in shape, lying just below the ribs 
and a little to the left side of the body. It is closed at 



DIGESTION 



47 



both ends by small folds or valves. The valve between 
the oesophagus and the stomach ordinarily prevents the 
food from going back into the oesophagus. Sometimes, 
however, when ill- 



•Oesophagta 




-Pancreas 
dp/een 



ness causes us to 
vomit or " throw 
up," the valve be- 
tween the stomach 
and the oesophagus 
opens and allows 
the food to return 
to the mouth. The 
valve at the lower 
end, which con- 
nects with the tube 
called the intestine, 
prevents the food 
from leaving the 
stomach too soon. 
Figure 13 shows 
the stomach with 
its valves. The 
stomach itself is 
elastic, and will 
stretch so as to 
hold a large amount 
of food, but it 

shrinks again as soon as the food passes out. The 
stomach of an ordinary grown-up person can hold three 
pints of food very comfortably. 



Fig. 13. — The Digestive Organs op 
the Abdomen. 



48 



PHYSIOLOGY AND HYGIENE 



The outer walls of the stomach consist principally of 
muscular fibers which run around it in various directions, 
some crosswise, some lengthwise, and some obliquely. 
As these fibers contract and relax, they cause the 
stomach to undergo a variety of motions, which mix 
together the different foods inside and keep them 
moving around and around. As long as the food 
remains in the stomach it is thus kept in constant 
motion. 

The inner lining of the stomach contains hundreds 

Inner Surface of Stomach 




Fia. 14. 



Gastric 
G/ancfs 



Musc/es 



Muscles 



A Section of the Wall op the Stomach. 

Highly magnified. 



of thousands of tiny glands. Each of these glands 
is shaped somewhat like a little bottle, with its mouth 
opening into the stomach, as shown in Figure 14. The 



DIGESTION 49 

glands produce a liquid called gastric juice, which is 
poured out of their mouths into the stomach. 

Action of the Gastric Juice. — As soon as the food 
enters the stomach, the glands begin to pour gastric 
juice upon it. At the same time the stomach, by con- 
tracting, begins to churn the food, and mix it with 
the gastric juice. In a short time the two are com- 
pletely mixed, so that the gastric juice can begin to 
act upon the food and produce in it the changes that 
we call digestion. 

Action on Starch. — When we chewed our mouthful 
of bread until it turned sweet, we found that the 
saliva had changed some of the starch in the bread 
to sugar. This digestive action of the saliva upon the 
starch is stopped as soon as the gastric juice begins to 
work upon the food. This is because the gastric juice 
is an acid, and we have already learned that the presence 
of anything sour prevents the action of the saliva upon 
starch. The starch, then, is not digested in the 
stomach, but it will be taken care of farther on. 

Action on Meats. — A portion of the work of the gas- 
tric juice is to break the food into small parts. Meat 
is made up of a great number of tiny threads, called 
muscle fibers, which are glued together by a material 
that holds them in little bundles. The gastric juice 
dissolves this gluey material, and the fibers fall apart. 
Just as soon as the juice gets them separated it pro- 
ceeds to act upon each one separately, changing it 
to a liquid form ready for the blood to take up, or, 
as we say, digesting it. We have noticed (see Fig. 2) 



50 



PHYSIOLOGY AND HYGIENE 



that the fat is in little sacs held together by a connect- 
ing mass of threads. Both the sacs and the threads 
are dissolved by the gastric juice, so that the fat floats 
about freely in the stomach. 

Action on Proteids. — It is also a portion of the work 

of the gastric juice to 



Oesophagus 



Stomach 

^htdrgeMestine 

4\-£millJntestLne 





get the proteids ready 
for the blood to use as 
the building material of 
the body. We found, 
when we cooked the 
albumen of the egg and 
when we caught the glu- 
ten of flour in muslin 
cloth, that these proteids 
could not be dissolved in 
water. But, until these 
substances are in liquid 
form, they cannot be 
taken up by the blood. 
What the gastric juice 
does for the proteids is 
to change them in such a 
way as to make it possible 
for them to dissolve in 
the water that is in the stomach. After the gastric juice 
has done its work, a part of these glutens, albumens, and 
caseins become dissolved and are ready to enter the blood. 
Usually a part of the proteid food leaves the stomach 
undissolved and is changed to a liquid form later. 



Fig. 15. — Showing the Location 
of the Digestive Organs. 



DIGESTION 51 

Action on Milk. — After a hearty meal a baby often 
throws up a part of his milk in a curdled condition. 
This does not mean that the stomach is "sour," but 
simply that the child has overfilled his stomach. The 
milk ought to be curdled in the stomach, and if it 
did not curdle, it would mean that the stomach was 
out of order. The curdliug has been caused by the 
gastric juice. The gastric juice in a baby's stomach 
curdles the milk more readily than that in the stomach 
of a grown person, but under all circumstances curdling 
is the first step in the healthful digestion of the milk. 
The curdled milk looks exactly as if it had soured. 

We can see just how the curdling takes place by put- 
ting a teaspoonful of rennet or a rennet tablet (to be 
had at the druggist's) into a cup of milk warmed to 
about the temperature of the body (98°). In the 
course of half an hour the milk will be curdled. Notice 
that the curd, which is casein, is a solid mass. In the 
stomach this curd is later dissolved again. 

Chyme. — We swallow our food in the form of solid 
meat, solid bread, and liquid milk, and in a short time, 
from an hour and a half to three hours, it becomes 
quite changed. It is now a thick liquid. The fats, 
freed from their sacs, as we have seen, have been melted 
by the heat of the body; the meat has been divided 
into threads and partly dissolved; the sugars have been 
dissolved in the water; some of the starches have been 
turned to sugar and also dissolved; while the milk has 
been curdled and partly turned to liquid form again. 
These materials have been churned by the motions of 



52 PHYSIOLOGY AND HYGIENE 

the stomach until they are thoroughly mixed together. 
They now form a gray, slimy mass called chyme. 

Although we pay no attention to the matter and 
think little about it, our hearts continue their accus- 
tomed beating, hour after hour and day after day. 
And so it is with the stomach's work. We do nothing 
to supply the materials required by the body except to 
eat when we are hungry, and yet the wonderful work 
of digestion goes on, usually without inconvenience 
to us. 

A Few Good Rules. — Though we cannot do much to 
help the stomach in the churning and digesting process, 
we may assist it by our manner of eating our food. 
If we are too thoughtless of the rights of the stomach, 
we are certain to receive our just punishment sooner 
or later in the form of indigestion and dyspepsia. 

We can aid the stomach and preserve our own health 
by following a few simple rules. 

We should eat slowly and be sure that the food is 
well chewed before it is swallowed. The habit of eat- 
ing often between meals is very trying to the stomach, 
since it keeps the gastric glands in constant action. We 
should never eat a hearty meal when we are either very 
tired or very warm; it is wise to rest first. No hard 
work, either mental or physical, should be entered upon 
for at least half an hour after a hearty meal. This is 
the stomach's busiest time ; we should help it as much 
as possible by keeping the rest of the body quiet. 

We should be careful as to the quantity of water that 
we drink with our meals. Some water is required, but 



DIGESTION 53 

the food should never be "washed down" with water. 

Nor is it well to drink much water immediately before 

a meal. Ice-water, if drunk at all, should be sipped 

slowly, so that as it passes down through the throat, it 

may be warmed more nearly to the temperature of the 

stomach. 

FOOD IN THE INTESTINES 

After the food has spent from one to two hours turn- 
ing around and around in the stomach, the fold forming 
the valve or lid to the intestine opens and allows a small 
amount to pass out. The contents of the stomach thus 
from time to time pass into the intestines, until, at the 
end of three or four hours, the outlet relaxes and allows 
the remaining food to leave the stomach, even though 
some of the particles may still be quite solid. The 
stomach is now empty, and, after a rest, is ready for the 
next meal. 

The Intestines. — The food which has passed through 
the opening at the lower and smaller end of the stomach 
enters the intestines, more commonly called the bowels. 
The intestines consist of a long tube, very much coiled, 
filling the larger part of the abdomen below the stom- 
ach, as is shown by Figures 13 and 15. The part which 
is connected with the stomach, or the small intestine, is 
from one to two inches in diameter, and about twenty 
feet long. The large intestine is about two and one 
half inches in diameter and five feet long. 

The Liver. — We all have seen the liver of the ox or 
calf either exposed for sale at the market or on the 
breakfast table cooked with bacon. The human liver 



54 PHYSIOLOGY AND HYGIENE 

resembles the ox liver very closely. It is of a dark 
red color, and lies a little above and at the right of 
the stomach. It is one of the largest organs in the 
body, weighing several pounds, and it is one of the 
most important. It produces a liquid called bile. The 
bile passes through a tube and empties into the intes- 
tines near the stomach. When digestion is not going 
on, the bile collects in a little sac at the lower side 
of the liver, known as the gall bladder. Figure 13 
shows the liver, the gall bladder, and its tube or duct. 

The Pancreas. —The pancreas is a long, somewhat 
thin gland, placed just below the stomach. This also 
produces a liquid secretion which passes through a tube 
and empties into the intestines. This liquid, which is 
called the pancreatic fluid, empties into the intestines 
with the bile. Thus the food from the stomach is 
mixed with the bile from the liver and the fluid from 
the pancreas almost as soon as it enters the intes- 
tines. Notice the pancreas, with its duct, as shown in 
Figure 13. 

Use of the Liver. — Probably most of us know from 
experience how a person looks and feels when he is 
"bilious." The skin becomes a dull yellow, the eyes 
lose their sparkle, and the person seems to lose all 
his ambition without being sufficiently ill to be con- 
fined to his bed. The trouble is that the bile has 
ceased to pass freely from the liver. The bile aids the 
pancreatic fluid in its work of digestion, especially on 
fats, tends to prevent decomposition in the contents of 
the intestines, and aids in the regularity of the action 



DIGESTION 55 

of the bowels. But the bile is, however, chiefly a waste 
product, and it pours into the intestines partly as a way 
of disposing of itself. The liver has several functions to 
perform ; one of the most important is to help to remove 
this waste material. When, for any reason, the bile 
cannot thus escape into the intestines, it passes back 
into the blood in the liver, and is then carried to all 
parts of the body, producing illness and turning the. 
skin to a peculiar yellow. We then say we are bilious. 

Changes in the Intestines. — As soon as the food enters 
the intestines it is mixed with the secretions from the 
liver and pancreas. Further changes are at once pro- 
duced in the food, principally by the pancreatic fluid. 
The pancreatic juice acts upon all kinds of food in such 
a way as to make liquid those not already dissolved. 

Starch. — We have learned that most of the starch 
escapes from the mouth without being turned into 
sugar by the saliva and passes into the stomach and 
out again to the intestines, still in the form of starch. 
But the pancreatic juice has just the same effect on 
starch as has saliva — it turns the starch to sugar. 
The pancreatic juice takes up and completes this work 
of changing starch into sugar. The sugar is then dis- 
solved like all of the other food. 

Proteids. — The pancreatic juice has the same effect 
upon the proteids as the gastric juice. It changes into a 
soluble form any proteids that may have passed into the 
intestines in solid state, whether they be the lean part 
of meat, the gluten of the wheat, or the casein of milk. 
The food in the intestines becomes more and more liquid. 



56 PHYSIOLOGY AND HYGIENE 

Fats. — The last we knew of the fats they formed an 
oily mixture in the stomach, where the gastric juices 
could not act upon them. When they pass into the 
intestines the pancreatic juice begins to digest them. 
We have already seen that when we shake olive oil 
with water, the water separates the oil into minute 
drops that float, making the liquid look milky. In a 
somewhat similar way the pancreatic juice acts upon 
the fats as they pass along the intestines. It breaks 
the fat into millions of tiny drops which are mixed with 
the contents of the intestines, giving the whole mass a 
milky white appearance. The breaking up of the fat 
into drops is the digestion of fat. The fat is not actu- 
ally dissolved like the sugar, but when it is broken up 
in this way the particles of fat are small enough to 
pass into the blood. 

Chyle. — The food was swallowed as solid bread, 
meat, and potatoes, but now, after from two to four 
hours or more, it has become in the intestines a milk- 
white liquid, somewhat thicker than milk, but not so 
thick as molasses. It is called chyle, and it contains 
most of the foods, dissolved into liquid form. The 
food is now ready to be absorbed into the blood vessels. 

THE DIGESTIBILITY OF FOODS 

If our food were not digested, it would be of no more 
use to us than stones, for it could not be taken into the 
blood. People who have weak digestive organs suffer 
from lack of food, no matter how much they eat. For 
this reason the value of the food we eat depends as 



DIGESTION 



57 



much upon whether it is easily digested as upon the 
food substances that it contains. 

Cheese, for example, contains a very large amount 
of valuable food, but it is so hard to digest that it is 
less useful than meat, which, although it contains less 
food than cheese, digests more easily. Beans are in 
some respects a more nourishing food than meat, but as 
they do not digest so easily, much of their value may 
be lost, passing away in the waste. 

In choosing what we shall eat we should be careful 
not to load the stomach with food hard to digest. 
Although it is perfectly safe, if we are strong and well, 
to eat some foods that do not digest easily, we should 
not do so frequently. The following table will give us 
a little idea of some of the more easily digested foods 
and some of those less easily digested : — 



Foods Easy to Digest 


Foods Difficult to Digest 


Milk 


Fried foods 


Bread 


Beans and peas 


Rice 


Hard-boiled eggs 


Raw oysters 


Pork 


Soft-boiled eggs 


Veal 


Boiled beef 


Cheese 


Mutton 




Boiled chicken 




Broiled meats 





Boiled or broiled foods are, in general, more quickly 
digested than those that are roasted, because boiling 



58 



PHYSIOLOGY AND HYGIENE 



softens the solid foods so that the digestive fluids can 
act upon them. Fried foods are more difficult to digest 
than the same foods cooked in any other way, since 
the frying is apt to soak the food with fat, which makes 
it difficult for the digestive juices to act. 



blood Vessels 



Lacttak or 
'rnph Vessels 



HOW THE FOOD GETS INTO THE BLOOD 

All this process has not yet put the food where it 
can be used to build up, repair, warm, and provide 
muscular power for the body. We are now ready for 
the final chapter of our story — how the digested food 
gets into the blood. 

We have learned that by the time the food has been 

in the intestines 
from two to four 
hours it has all 
become digested 
and turned into 
chyle. The long in- 
testinal tube which 
holds the chyle, is 
not loose in the 
body, but is held 
in position by a thin 
sheet. Such a sheet 
is called a mem- 
brane, and this par- 
ticular one is the mesentery. It is folded many times 
and is wrapped around the intestines as shown in Figure 
16. There are many blood vessels in the mesentery, 




Intestm 



Fig. 16. — A Bit of the Intestine. 

Showing how it is held in position by the 

mesentery. 



DIGESTION 



59 



some of them carrying blood to the intestines, and 
others carrying the same blood away again. These 
blood vessels take away a large part of the digested food. 
A bit of the intestinal wall is shown in Figure 17. 
The wall is rather thick and has two layers of muscles. 




Fig. 17. — A Bit of the Intestine. 

Showing the muscles, glands, and the numerous villi on its 

under surface. Moderately magnified. 

The inside surface is covered with tiny projections, 
like little fingers, extending inward. They are called 
villi. Figure 17 shows some of the villi enlarged, so 
that we may see what they are like. Villi are really 
so very tiny that they can only just be seen with the 
naked eye. There are millions of them, so many that 
they line the whole inside of the intestines, giving it a 
soft, velvety surface. 

Duties of the Villi. — The villi are very interesting to 
study, for they take the digested food out of the intes- 
tines and give it to the blood. Unlike the glands of 



60 



PHYSIOLOGY AND HYGIENE 



Epithelium 



blood 
Vessel 



the stomach, of which we have learned, these villi have 
no opening into the intestines. Their walls, however, 
are so thin and so delicate that the dissolved food can 
pass through them readily. A single one of these little 

bodies, much magnified, is 
shown in Figure 18. It is 
covered on the outside with 
tiny cells, which form the 
epithelium. Inside there 
are a great many minute 
blood vessels. One blood 
vessel, the artery, brings 
blood into the villus, and 
another, the vein, takes it 
away. The artery brings 
the blood from the heart; 
the vein carries it away to 
the liver. 

Just how the villi take 

the food and send it where 

it belongs is a particularly 

interesting chapter in our 

story of digestion. The 

white chyle moving along 

the intestines bathes the 

villi as it passes. Each little 

villus is constantly at work 

taking the digested food from the chyle as it comes 

along, leaving the undigested and waste matters. The 

dissolved sugars and albumens pass through the thin 




i A Cell 



vei/v, 



-Artery 

Tig, 18. — A Single Villus. 
Highly magnified. 



Lymph Vessel 
or Lactt 



DIGESTION 



61 



membrane into the inside of the villus. Even the par- 
ticles of fat are seized and passed into the inside. Thus 
as the food passes on through the intestines, more and 
more of it is taken up by villi, until most of the useful 
part has been removed. The way in which this food is 
taken into the intestines is illustrated in Figure 19. A 
bladder is tied tightly 
upon a tube and filled 
with water, and the 
whole is then lowered 
into a dish containing 
some sugar dissolved in 
water. It will be found 
after a little time that 
the water inside of the 
bladder has become 
sweet. The sugar has 
passed from the dish 
into the bladder. In 
much the same way the 
sugars and other foods 
pass from the intestines 
into the villi. 

After the food gets into the villi it does not all go in 
the same direction. The sugars, proteids, water, and 
salt are taken out of the villi by their tiny blood vessels 
and are carried away in the blood to the liver. Of 
course the starch has already been turned to sugar by 
the digestive processes, so that all the foods go to the 
liver, except the fat. 




Fig. 19. — A simple device for show- 
ing how foods may pass through 
membranes, as they do when they 
enter the villus. 



62 PHYSIOLOGY AND HYGIENE 

The fat takes a different direction. It does not enter 
the blood vessels of the villi at all. The middle of the 
villus, as shown in Figure 18, is a clear space called a 
lymph vessel or lacteal. This opening or tube is made 
to receive the fat, and the little drops of fat pass 
directly into it. The vessels are called lacteals, which 
means milk holders, because the liquid fat with which 
they are filled is white like milk. After taking the fat 
from the intestines the lymph vessels empty it into 
larger, similar vessels and these empty into still larger 
ones which pass through the sheet of membrane sur- 
rounding the intestines. The large lacteals pass up 
through the chest, back of the heart, and empty the fat 
into one of the large blood vessels in the neck, so that all 
of the absorbed food material finally reaches the blood. 

There are thus in the membrane shown in Figure 16 
three sets of tubes : 1. Blood vessels bringing blood to 
the intestines. 2. Other blood vessels carrying the blood 
which has taken up food, from the intestines to the liver. 
3. Lacteals carrying fat to the blood vessels in the neck. 

UNDIGESTED PORTIONS OF THE FOOD 

We have learned that the food passes from the 
stomach through the intestines. The material is kept 
moving by a contraction of the wall of the intestines. 
This contraction causes a gentle writhing motion of 
the intestines, which forces the food slowly along. 
The movement is somewhat similar to the wriggling 
of an earthworm as it tries to make its way along 
the surface of the ground. As the food mass passes on, 



DIGESTION 63 

the villi take up more and more of what can serve the 
body as real food, together with much of the water. 
Finally, very little is left in the intestines except undi- 
gested refuse, together with excretions, like bile, which 
are of no further use. These are waste materials. As 
more and more of the water and dissolved food are 
absorbed, the waste materials become quite solid, until 
they pass out of the body. The bowels should get rid 
of the waste material every day. Regular habits in 
this respect are necessary for avoidance of discomfort 
and of sickness. 

Now the story of food digestion is nearly completed. 
Let us recall briefly the history of our piece of bread 
and butter. It was carried to the mouth, and was 
bitten off and chewed by the teeth. With the aid of 
the saliva it was moistened and then swallowed. After 
a safe passage over the windpipe, the oesophagus carried 
it to the stomach. There it was thoroughly churned 
and mixed with gastric juice. Little by little it passed 
from the stomach into the intestines, was mingled with 
the bile and pancreatic juice, and then the digested part 
was taken up by the villi, leaving the waste materials 
to be discarded. As we shall see later, the food material 
finally reaches through the blood all the parts of the 
body which need it for growth or work. 



64 PHYSIOLOGY AND HYGIENE 



QUESTIONS 

1. What is meant by digestion ? 

2. Why is it necessary to digest food ? 

3. What are the parts of the mouth ? 

4. Of what parts does a tooth consist ? 

5. How many permanent teeth are there? What are their 
names? 

6. What causes a tooth to decay? 

7. What and where are the salivary glands? 

8. What are the uses of saliva? 

9. What prevents food from passing into the windpipe instead 
of the oesophagus ? 

10. How does the stomach digest the food? 

11. What is the action of the gastric juices on meats? On 
proteids ? On milk ? 

12. What is chyme? 

13. What are the liver and the pancreas? 
14c. Of what use is the liver ? 

15. What changes are made in starch, proteids, and fats in the 
intestines? 

16. What is chyle? 

17. How does the food get into the blood? 

18. If you chew finely a piece of meat, does saliva start its 
digestion ? How would it be with bread ? 

19. Notice your method of swallowing, and see if you use your 
tongue. 

20. What part of a lunch of bread and butter is digested in the 
mouth ? What in the stomach ? What in the intestines ? 

21. Since cheese is made of milk, why is it not a good food for 
babies ? 



CHAPTER III 

FOOD HABITS AND COOKING 

Unwise habits with regard to eating and drinking 
are probably the cause of more sickness than anything 
else. Indigestion, which is very common, may fre- 
quently be remedied more easily by changing the habits 
of eating and drinking than by taking medicine. 

PROPER HABITS OF EATING 

Suppose a company of boys from different parts of 
the world should come together for a picnic. Their 
lunch baskets would contain a good variety of what the 
owners would consider delicacies. The American boy 
would probably have sandwiches and cake; the German, 
rye bread and sausages; the Chinese, some form of rice; 
the young Eskimo, a fish or a piece of seal. Each boy 
would be well nourished and satisfied, if only he had 
enough of his own kind of food. In other words, just 
what we eat is largely a matter of custom and climate. 

We are mistaken if we think we must have certain 
kinds of food, for we can adapt ourselves to almost 
anything, provided it is nutritious and digestible 
We have a very large variety of foods from which 
to choose, but it is wise to adapt the appetite to 

C5 



66 PHYSIOLOGY AND HYGIENE 

what is conveniently obtained. We should particularly 
guard against allowing ourselves to be controlled wholly 
by taste, and we should not refuse to eat what is whole- 
some just because we fancy it is not quite to our liking. 
Substances with very strong taste, like mustard, for in- 
stance, we may properly refuse whenever they are dis- 
tasteful, but there is no sensible reason for objecting to 
a dish of oatmeal; we can eat it, and learn to like it, if 
we will. 

Cost. — People with small incomes are likely to live 
principally upon starchy foods, such as bread, rice, or 
potatoes, because these are comparatively cheap. But 
we cannot live upon starch and sugar alone. We must 
all of us have some proteids. If we will remember that 
we can get our proteids cheapest in beans and cheese, 
we shall be able to make better use of our money than 
by spending it all for starchy foods. A simple meal of 
bread, butter, milk, cheese or meat, and some vege- 
tables, with perhaps a dessert of fruit or a simple pud- 
ding, is far better than a heavy dinner, with numerous 
courses. Some people make the mistake of having 
too many kinds of food at one meal, many of them 
highly seasoned. The pleasurable taste encourages 
us to eat more than the body requires, and the result 
is frequently a loss of healthy appetite. The man who 
spends a great deal of money for his food usually gets 
less pleasure from it than the one who lives upon plain 
foods varied by an occasional luxury. 

Times for Eating. — Most people in this country eat 
three meals a day. In some countries four or five 



FOOD HABITS AND COOKING 67 

meals are the rule, in others only two or even one. 
Whatever our habit in this regard, we should eat at 
certain specified times, so that the stomach may be 
called upon to work regularly, and may also have a 
chance to rest. 

We frequently hear that candy is injurious, although 
we have learned that sugar is a useful food. The trouble 
is not with the candy, but with our abuse of it. If we 
have sweets in our possession, we are apt to be munch- 
ing them all day long, keeping the stomach constantly 
at work. Moreover, the pleasant taste of the candy is 
likely to make us eat too much, so that we suffer from 
overeating. Some people, especially children, like to be 
eating all the time. This is very unjust to the stomach. 
Continuous good health is impossible unless the stomach 
and other digestive organs are given regular times to 
rest as well as to work. 

Although breakfast is an important meal, it need not 
be a heavy one. Nor, on the other hand, ought we to 
make too light a meal of it. This error often leads to 
headache, faintness, and weakness before the noon meal. 
Fruit, oatmeal or some other cereal, and eggs, with 
bread, form an excellent breakfast. There is no better 
drink to go with it than water. Milk, chocolate or 
cocoa may also be taken, but we should remember that 
they are foods as well as drinks. The heartiest meal 
should be in the middle or at the close of the day, and 
should be followed by rest of at least an hour. A little 
food before going to sleep at night helps some to rest 
easily. A glass of hot milk taken just before a person 



68 PHYSIOLOGY AND HYGIENE 

retires is frequently an excellent remedy for habitual 
wakefulness. 

The Appetite as a Guide. — When we are in need of 
food we feel hungry, and when we need water we are 
thirsty. Hunger and thirst are, then, the guides given 
us by nature to indicate the want of food and water. 
If we treat them wisely, they guide us well, so long as 
we are in good health. But these appetites may be 
abused so that we cannot follow them safely. Some 
people, especially children, continue to eat anything 
that they happen to like particularly, even after their 
desire for food is gone, and they keep on drinking 
pleasant tasting liquids after the thirst is quenched. 
This is almost sure to do injury. 

We should eat to satisfy the desire for food. One 
who continues eating after the body has taken suffi- 
cient nourishment is both foolish and intemperate. 
Overindulgence in eating is probably one of the most 
common causes of ill health. It is always wise to stop 
eating as soon as the food ceases to be relished as much 
as it was when the meal began, instead of continuing 
to eat until there is a feeling of fullness in the stom- 
ach. If we make this a habit, we are not likely to 
suffer either from eating too little or from eating too 
much. 

Pleasure in Eating. — The old proverb, " Laugh and 
grow fat," is a saying with sound sense behind it. 
Good temper and merriment certainly aid digestion. 
Mealtimes should be among the pleasantest occasions 
of the day. There is no reason why we should not 



FOOD HABITS AND COOKING 69 

enjoy partaking of the food, as well as take pleasure 
in the companionship of those who share our table. 
This enjoyment is lost in many homes, not only through 
making mealtimes the occasion for disputes, but by the 
unfortunate habit of " bolting " the food, which renders 
conversation an impossibility, and takes away all pleas- 
ure in the food itself. 

Overeating, eating rich foods in great variety, and 
eating too frequently and rapidly, are the causes of 
most of the indigestion so generally suffered. Few 
maladies occasion more discomfort than indigestion. 
When one must always ask whether this or that article 
of food will agree with him or give him pain, a great 
part of his pleasure in life is gone, and it is no wonder 
that he becomes soured in disposition, as so many dys- 
peptics do. Children usually, however, have strong 
digestive organs, and the boy or girl who will eat whole- 
some food regularly and slowly will probably have good 
digestion throughout life. The use of too much food or of 
food that is too rich is likely to lead to lasting discomfort. 

THE HABIT OF USING ALCOHOL 

Alcohol and Digestion. — Some people try to stimulate 
digestion in various ways, most commonly by the use of 
alcoholic drinks, especially wine. But it is a mistake 
for a boy or girl or any healthy person to use alcohol 
for this purpose. It does not aid digestion in any nor- 
mal individual. In this connection it should be re- 
garded as a drug, and be used, if at all, only under 
medical direction. 



TO PHYSIOLOGY AND HYGIENE 

Many persons use alcoholic drinks for this or some 
other purpose until they get into such condition that 
they think they cannot properly digest food without 
using wine or alcohol in some form, to stimulate the 
weakened digestive powers. They have become like a 
horse that will not travel without a whip. The con- 
tinued use of the alcohol is very likely to injure the 
stomach so that finally proper digestion is impossible. 
The person who wishes to grow up strong and vigorous, 
with healthy digestive organs, will let alcoholic drinks 
entirely alone. 

The Appetite for Alcohol. — There is one character- 
istic of all alcoholic drinks that makes them very 
dangerous. If a person eats ordinary foods, such as 
sugars and starches, he may sometimes eat too much ; 
but this does not develop a desire for larger amounts 
of the food. We may eat enough candy to make us 
ill, but this does not produce a craving for candy. On 
the contrary, it sometimes even causes us to lose all 
fondness for sweets, at least for a time. But alcohol 
frequently acts in a different way, its use creating a 
desire for more. 

The first glass a person takes is generally not pleas- 
ing; but if he continues to use alcoholic drinks, after 
a little he comes to enjoy the taste and the effect, and 
in time he finds that he has a craving for it, and feels a 
certain lack if this craving is not satisfied. Whereas at 
first a small amount of the alcoholic drink was all he 
wanted, he soon becomes accustomed to this, and al- 
most without knowing it he takes a little more. This 



FOOD HABITS AND COOKING 71 

later fails to satisfy him, and, not realizing how serious 
a matter it is, he increases the amount of alcohol he 
uses, sometimes by drinking larger amounts of weaker 
liquors, and sometimes by taking stronger ones. And 
so the appetite grows until he finds it almost impossible 
to conquer it. In other words, instead of being a free 
man he has become a slave, and frequently a willing slave, 
for the use of alcohol regularly and in large amounts 
ordinarily destroys all desire to live a healthful, clean life. 

In most cases the person who drinks does not know 
that the appetite is growing until it has become so 
strongly fixed as to do him great injury. In just this 
fact lies the greatest danger, for if he could realize how 
he is coming under the influence of the unfortunate 
habit, he would break it before it mastered him, and 
before it destroyed his will power. When that is gone 
the best of the person is lost. 

Now, it is true that people who use small amounts 
of alcohol are not immediately mastered by the habit. 
But it is equally true that the use of small amounts 
of alcohol may lead to the development of an appetite 
which in time will completely master the user. Habit- 
ual drunkards are made out of boys and girls who 
did not intend to use alcohol enough to injure them. 
Unfortunately, even science has no way of telling 
which people can drink alcohol without falling under 
the sway of its appetite. Strong people, as well as 
weak, give way to it. The moment a person begins 
to use alcoholic drinks, even in a mild way, he places 
himself in the class of people from whom drunkards 



72 PHYSIOLOGY AND HYGIENE 

may be made. The only safe way is to keep as far 
from the danger as possible, by letting drink abso- 
lutely alone. 

Intemperance in Eating and Drinking. — Although 
alcohol is likely to do us more harm than any other 
kind of drink or any food, still we should be careful to 
avoid all forms of overindulgence. We may injure our- 
selves by eating too much candy or any other enjoyable 
food. We should make up our minds to be moderate 
in all our eating and to avoid alcoholic drinks alto- 
gether, for in this way only can we insure the strong, 
healthful growth of the body, and only thus shall we 
be able to do our share of the world's work. 

PURPOSES OF COOKING 

No one who, on entering the house tired and hungry 
after a half day at school, has been greeted with the 
appetizing odors coming from the kitchen, need be 
told that cooking has its advantages. We eat very 
few foods without cooking, except milk, a few vege- 
tables, and fruits. Most foods are not considered fit 
to eat until they are cooked. 

There are three purposes in cooking food. 

1. Cooking develops a flavor. — We have only to 
notice the difference in taste between raw beefsteak 
and the same steak broiled and ready for the table 
to comprehend how cooking improves the flavor. It 
is true that cooking injures the flavor of certain fruits, 
such as strawberries, but it improves the taste of all 
meats and most vegetables. 



FOOD HABITS AND COOKING 73 

2. Cooking makes food easier to digest. — The cooking 
of vegetable foods is usually necessary to enable us 
to digest them. Potatoes, for example, contain large 
amounts of starch; but it is shut up in little sacs of a 
kind of woody substance, as shown in Figure 5, and so 
long as the starch is in these sacs the digestive juices 
cannot get at it. The juices have little or no power to 
dissolve the sacs, and consequently raw potato cannot 
be digested. Cooking softens the woody sacs and sets 
the starch free. Moreover, it causes the starch grains 
themselves to burst and when burst they are more easily 
digested. We should remember that all starchy foods 
should be well cooked before they are eaten. The cook- 
ing of meats is not of great importance so far as mere 
ease of digestion is concerned. In fact, most meats are 
more easily digested if they are not cooked too much. 

3. Cooking removes danger from parasites, — Some of 
our foods contain minute living animals, called para- 
sites. Some of these, harmless in themselves, throw off 
products which are poisonous ; others are themselves 
dangerous, and might do us considerable injury if swal- 
lowed alive. Pork, especially, sometimes contains large 
numbers of very small living worms, which, if taken 
into our bodies alive, are likely to cause serious dis- 
ease, perhaps death. Pork has occasionally another 
parasite which may develop in the human stomach 
into a tapeworm several feet long. Heat kills the 
parasites, and pork, including ham, should therefore 
always be thoroughly cooked. Beef and mutton are 
less likely to contain these parasites, but neither should 



74 PHYSIOLOGY AND HYGIENE 

be eaten uncooked. We have already learned that milk 
is frequently cooked, or sterilized as we say, to destroy 
any disease bacteria it may contain. 

PRINCIPLES OF COOKING 

The ambitious girl who takes pride in her ability to 
make an appetizing cake or to prepare a dinner does 
not need to be taught the effect of cooking on the 
various articles of food. Neither does the boy who 
goes camping in the summer and gets his own meals. 
Nevertheless, there are certain principles underlying 
cooking that we cannot learn over stove or camp-fire, 
but which we can easily understand. We have already 
found by testing the white of an egg that cooking 
coagulates albumen. We know, too, from boiling 
starch, that cooking changes starch foods into pulpy 
masses. Experience in the kitchen has shown us that 
vegetables are softened by cooking, and that fatty sub- 
stances are melted or made liquid by the same process. 
In general, cooking softens foods so that they are made 
easier to chew and to digest. Another general prin- 
ciple which should be borne in mind in all cooking, is 
that proteids are coagulated by heat. This is especially 
important as related to beef tea and soups. 

Beef Tea. — If raw beef is cut fine and soaked in 
water, a part of the nutritious material is dissolved, 
and the liquid is good food as it stands. But if, 
after the beef has been soaked, the liquid is boiled, 
all of the dissolved material is coagulated and appears 
as a brownish scum. This can be separated from the 



FOOD HABITS AND COOKING 75 

rest by straining the liquid through a cloth. Beef tea 
is usually strained, the liquid being used and the scum 
thrown away. Such tea. is pleasant to the taste, but 
after the scum has been taken off it contains almost 
no food. Nothing is left except the salts and flavors. 
These are, however, frequently of use to invalids. The 
salts and flavors have a stimulating action on the diges- 
tive glands, and thus assist in giving the sick person 
an appetite, so that he can take, and more easily digest, 
real food. Beef tea is therefore of use in sickness or 
for persons with weak digestion ; but it should always, 
if possible, be taken together with something more sub- 
stantial. If the tea were made of finely minced beef put 
into cold water and very slowly heated, until quite hot, 
but without boiling, it would be very nutritious, for it 
would then contain the food material, which is not all 
coagulated except when actually boiled. 

Soups and Stews. — The straining out of the food 
applies also to the making of soups from meats and 
vegetables. The heat of boiling produces coagula- 
tion, and the clear liquid, which is strained off and 
served as the soup, contains little more than the salts 
and flavors. Soups are not, however, usually regarded 
as foods. They are served at the beginning of a meal 
as a slight stimulant to digestion. Stews, on the other 
hand, the whole cooked mass of which is eaten, are 
nourishing and useful foods. Though the proteid has 
been coagulated, this does not injure the stew as a food, 
since the coagulated material as well as the liquid is 
eaten 



76 PHYSIOLOGY AND HYGIENE 

METHODS OF COOKING 

If some one should ask' us how our mothers, cook, 
the most natural answer would be, u In all sorts of 
ways." The answer would be correct in a certain 
sense, and yet all kinds of cooking may be included 
under the four heads of boiling, baking, broiling^ and 
frying. 

We put a cover on top of the kettle of boiling meat 
to hinder the escape of the steam and the odor. Simi- 
larly, whenever we can, we put a cover or crust around 
the object which is being cooked, to keep all the food 
material and flavors inside. This may be done by heat- 
ing the object very hot when the cooking begins. Thus 
a crust is formed on the outside of the loaf of baking 
bread. The high heat forms a similar protective coat 
around the meat by hardening the proteid and so 
keeping the juices and flavors within. 

Boiling. — Boiling is one of the commonest and best 
methods of cooking, although it does not produce the 
finest flavors The article is cooked or boiled in 
water. One of the standing rules of housekeeping is, 
" If you want to have the richness in the liquid, you 
must put the article into cold water and heat slowly ; 
if you want the richness in the article itself, it must 
be put into boiling water." So vegetables must be 
dropped into boiling water, while meat for stews 
should be put upon the stove in cold water. If the 
meat is placed in boiling water, a coat is formed on 
the outside at once, and then the whole may be allowed 



FOOD HABITS AND COOKING 77 

to simmer over the fire for a long time without much 
further loss. Meat cooked thus will retain its juices 
and have an excellent flavor, while the water in which 
it is cooked will contain practically nothing of value. 
The liquid of the stew, on the other hand, is to be 
eaten with the solid matter, so the meat should be 
placed in cold water and then allowed to simmer 
slowly, in order that the liquid may contain part of 
the food. Stewing is an economical method of cook- 
ing, since in this way nothing of the original food is 
lost. 

Baking or Roasting. — Baking and roasting are two 
good methods of cooking which differ slightly from 
each other, but are similar in principle. The food 
is cooked in hot air, either in an oven or over a hot 
fire. When the food is cooked over the open fire we 
call it roasting ; when cooked in an oven, we commonly 
speak of it as baking, or, in the case of meats, we call 
it roasting. As the heat causes the liquid juices, 
especially of meat, to ooze to the surface, it is best to 
prevent the loss of these juices as far as possible. This 
is done, as in boiling, by heating the meat very hot at 
the beginning, so that a crust may be formed. The 
flavor and richness of the meat are much improved by 
pouring over it, say once in every fifteen minutes, the 
liquids which ooze out, a process called basting. If 
there is not sufficient liquid for this purpose, melted 
butter or suet, or even salt water is used. In baking 
bread and cake it is also desirable to use high heat at 
the start. 



78 PHYSIOLOGY AND HYGIENE 

Broiling. — One of the quickest and most desirable 
ways of cooking is broiling. Especial care should be 
taken to begin the cooking over a very hot fire in order 
that the surface of the meat may be quickly seared 
over, and the juices thus kept in it. 

Frying. — Frying is a method of cooking very com- 
mon, but not wholesome. As the food is cooked in hot 
fat, butter, suet, or olive oil, it is apt to become satu* 
rated with the fat. While fat of itself is nutritious, 
food soaked in it is very difficult to digest. To fry 
with the least injury to the food, there should be an 
abundance of fat, and it should be very hot. The high 
heat, as in other methods of cooking, forms a crust on 
the outside, which prevents, in considerable measure, 
the fat from getting into the food. 

Yeast and Baking Powder. — To make bread we mix 
flour with water, or milk, add yeast, and set the mix- 
ture in a warm place to "rise." The yeast grows in 
the bread, producing a very small amount of alcohol 
and a gas called carbon dioxide. The bubbles of gas 
appear in the dough, causing it to rise up like a sponge. 
In baking, both the alcohol and the gas are driven off 
by the heat, but the bread is filled with the little holes 
which were previously occupied by the carbon dioxide. 
This makes the bread "light," and easy to masticate 
and digest. Similar bubbles are made in cake and 
biscuit by putting baking powder into the dough. As 
baking powder produces the gas very quickly, it is 
adapted to rapid baking. To develop the necessary gas 
with yeast requires that the dough rise for several hours. 



FOOD HABITS AND COOKING 79 



QUESTIONS 

1. Why does an Eskimo eat fish and seal, while a Chinaman 
eats rice ? 

2. What facts should be considered in choosing our diet ? 

3. What kinds of food should be used together? 

4. When should we eat ? 

5. Is food with a pleasant taste more useful to the body than 
food without flavor ? Why ? 

6. How can we best enjoy our food? 

7. Why is rapid eating unwise? 

8. What effect has alcohol on digestion? 

9. How is an appetite for alcohol developed? 

10. What are the purposes of cooking ? 

11. How does cooking make a potato easier to digest? 

12. What does cooking generally do to food ? 

13. Why is a stew nutritious while beef tea is only a stimulant? 

14. What are the three methods of cooking ? 

15. How is cooking done by boiling ? 

16. How is food cooked by baking ? 

17. Why is fried food apt to be indigestible ? 

18. What foods may properly be eaten without cooking? 

19. What do yeast and baking powder do to food ? 

20. Why is plain food more healthful than rich food? 



CHAPTER IV 
CIRCULATION 

Every house in a large city is supplied with water 
from faucets. The water is carried to the house by 
pipes laid in the ground, and the pipes come from 
a reservoir which supplies the whole city. In many 
places a large pump near the reservoir forces the water 
into the pipes. If the pump stops working, the water 
throughout the city ceases to run. 

We have seen how the food which we have eaten 
gets into the blood. This food is needed in all parts 
of the body. It is carried to the arms, the head, and 
the various organs by the blood vessels, very much as 
the city is supplied with water by the water pipes. 
The blood vessels are tubes running through the body, 
dividing into branches, and these again into smaller 
branches, so that every organ of the body, no matter 
how small it may be, has at least one. The heart acts 
as the pumping station, and by it the blood is kept in 
constant motion. 

THE BLOOD 

Let us see what this liquid is which flows so con- 
stantly through the blood vessels. We already know 
that it contains the part of the food we have eaten 

80 



CIRCULATION 



81 



which has been dissolved and absorbed from the intes- 
tines. But it has in it other materials besides. The 
blood that oozes from the finger when we have a cut 
looks bright red. If, however, we look at it through a 
microscope, we find that the liquid itself is almost as 
clear as water. In fact, the liquid part of the blood, 
called blood plasma, is largely water, although several 
substances are dissolved in it. The red color is pro- 
duced by millions of little red bodies floating about in 
the liquid. These minute bodies are called corpuscles. 
Red Corpuscles. — The most prominent cf the solid 
bodies in the blood are the red corpuscles. These are 

„ . .".yelled Corpuscle 

»; '.*?;'>•' Plasma 

M/te '\^:0SMm' :; ^ : ' : ' : / / ' Corpuscles 
Corpuscle **%%$%£&''-'* 

Fig. 20. — A Little Blood, as it appears under 
a Microscope. 



shown in Figure 20. They are small, thin disks, cir- 
cular in shape. As may be seen from (7, they are slightly 
thinner in the center than at the edge. They are very 
small, only about 3^^ of an inch in diameter, and 



82 PHYSIOLOGY AND HYGIENE 

consequently they are invisible except through a micro- 
scope. They are present in the blood in immense num- 
bers, there being some 5,000,000 of them in a very small 
drop. Each red corpuscle contains a red substance 
called hemoglobin. The important work performed by 
the red corpuscles we shall study in a later chapter 

White Corpuscles. — The white corpuscles act as the 
street-cleaners in the body. They are fewer in num- 
ber than the red corpuscles. They are transparent, 
and of a slightly bluish appearance. They have no 
definite shape, and in fact they are changing shape 
constantly, although they are most commonly some- 
what spherical, as shown in Figure 20. All the cor- 
puscles, both white and red, flow through the blood 
vessels with the blood. The red corpuscles can go only 
where the blood carries them; but the white corpuscles 
sometimes crawl out of the blood vessels entirely, push- 
ing their way through the walls. They then travel 
around independently among the muscles and various 
parts of the body. There they catch and carry off 
any minute irritating substances which might produce 
trouble and perhaps disease, if allowed to remain. Thus 
the white corpuscles of the blood are believed to have 
a very important part in warding off certain diseases. 

WHAT MAKES THE BLOOD FLOW 

The Heart. — The heart is situated in the chest a little 
below the neck and slightly on the left side, where, as 
we know, its beating may be felt. In an adult, the 
heart is about the size of a man's fist, and is somewhat 



CIRCULATION 



83 



pear-shaped, as shown in Figure 21. When in the nat- 
ural position, the apex, or small end, is turned down- 
ward and a little to the left. As long as a person lives, 
his heart continues to pump the blood through his blood 

vessels, so that the 

To head 



motion of the 
and of the 
never ceases. 
a pump, the 



blood 
heart 
Like 
heart 



To Arm 



'To Arm 



Artery 
on 



(Aorta) 



Left . , 
Aur/cfo 




has tubes entering it 
on one side bringing 
the blood in, and 
others on the oppo- 
site side carrying the 
blood away from it. 
The blood vessels 
bringing blood to 
the heart are called 
veins ; those carry- 
ing it away are called 
arteries. In Figure 
22 (facing p. 84) the 
arteries are colored 
red, the veins, blue. 

If we cut open the 
heart of some large 

animal, such as a sheep or an ox, we shall find that, 
like the human heart, it contains four cavities, as 
shown in Figures 23 and 24. The two cavities on the 
right side, called the right auricle and right ventricle, 



Aorta 



Fig. 21. — The Heart. 

Showing the veins and arteries con- 
nected with it. 



84 



PHYSIOLOGY AND HYGIENE 




Fig. 23. — The Right Side op 
the Heart. 



are connected with each other. The two on the other 
side, the left auricle and the left ventricle, are also con- 
nected with each other There is no connection be 
From* Head tween the two sides of 

the heart ; the blood can 
not flow directly from one 
side to the other. 

As the heart beats, 
blood which has just com- 
pleted the round of the 
body, and is full of im- 
purities which it has 
gathered, flows into the 
right auricle through the 
large veins from the head 
and body, indicated in Figure 23, and fills both the right 
auricle and the right ventricle. 
Then the heart contracts, that 
is, the muscles of the walls press 
the blood out, as we squeeze the 
juice out of a lemon by closing 
the hand tightly about it. When 
the heart contracts, the blood 
forces its way into the pulmo- 
nary artery, shown in Figure 23. 
The pulmonary artery carries it 
to the lungs to be purified. 

From the lungs the purified 
blood comes back to the heart again, this time by veins 
which send it into the upper of the two chambers at 



From Lwjw 




Fig. 24. — The Left Side 
of the Heart. 



CIRCULATION 85 

the left side of the heart, that is, into the left auricle ; 
thence it goes to the left ventricle, as shown in Figure 24, 
and by this it is sent through the large artery (the aorta, 
Figs. 22 and 24) in all directions through the body. Thus 
every time the heart beats, one side of it takes blood in 
from the head and body, sending it to the lungs, and at 
the same time the other side of the heart takes blood 
in from the lungs and sends it out through the body. 

In order to keep the blood flowing in the right direc- 
tion and to prevent its flowing backward, the heart con- 
tains several valves. These are folds inside the heart. 
When open, as in Figure 23, they allow blood to pass 
freely in the direction indicated by the arrow; when 
lifted, as in Figure 24, they completely close the opening 
between the auricle and the ventricle and prevent blood 
from being forced back into the auricle when the ven- 
tricle contracts. As soon as the heart relaxes, they 
open again and allow the ventricle to fill up once more. 
There are also some valves called semilunar valves 
(shown in Fig. 23), which in a similar way prevent 
blood from flowing back from the artery into the heart. 

The Beating of the Heart. — The heart never seems to 
get tired. All day and all night our whole lives through 
it keeps at its work of pumping the blood. The heart 
of a grown person beats about seventy times a minute, 
that of a child somewhat faster. It spends about 
three tenths of a second in beating, and then rests 
for four tenths of a second. In this way it really 
works less time than it rests, only instead of working 
in the daytime and resting at night, like the body in 



86 PHYSIOLOGY AND HYGIENE 

general, it does a bit of its work and then rests. In 
this way it is able to keep beating without becoming 
worn out. When we are in good health the heart beat 
is strong ; it weakens when we are ill. 

One reason why the use of tobacco and alcohol is 
injurious is that they are likely to weaken the proper 
action of the heart. Both alcohol and tobacco are very 
likely to cause heart difficulties, particularly if used 
by young people. Nearly every boy knows, from his 
own observation, that neither the habitual smoker nor 
the youth who uses alcohol wins in the athletic contest. 

The Pulse. — When a stone is thrown into a pond, the 
water is disturbed in the form of a circular wave which 
grows larger and larger, but all the time lessens in 
height, until it disappears. A somewhat similar effect 
is produced by the heart as it forces the blood into the 
arteries. The wave of pressure produced by the heart 
is felt all through the arteries, though it is less strong the 
farther it is from the heart. The wave causes a slight 
swelling of the arteries as the blood passes. The artery 
at the wrist is so near the surface that we can feel the 
wave, known as the pulse. 

The pulse can be found in any of the arteries where 
they are near the surface; but as most of them are 
deep in the muscles, there are few places where we can 
feel the throbbing. The usual place for testing the 
pulse beat is at the wrist, but it can be felt at the neck, 
just under the lower jaw, and also at the temples. By 
feeling of the pulse the physician can obtain consider- 
able information regarding the general condition of the 
patient's health. 



CIRCULATION 87 

BLOOD VESSELS 

Arteries, — When the blood is forced out of the heart 
from the left ventricle it passes into the large artery 
shown as red in Figure 22. This serves as the main 
artery to supply the body. The artery bends over to 
the left and runs down the body, giving off several 
branches on its way. The first branches extend to the 
head and the arms, while others lead to the stomach 
and the intestines, and still others run down into the 
legs. This main artery thus supplies blood to all parts 
of the body, just as the water main furnishes water 
for every house. The farther the branching arteries 
are from the heart the smaller they become, until finally 
each is divided into thousands of minute tubes which 
enter every organ of the body. 

Capillaries. — If we should follow up a single one of 
the minute branches of an artery, we should find that it 
ends in a set of even smaller tubes, like those shown in 
Figure 25. These are called capillaries. The capillaries 
are too small to be seen except with the aid of a micro- 
scope. They divide into many branches which come 
together in a somewhat irregular manner, differing in 
different localities, as shown in the figure. The blood 
flows from the small arteries into these capillaries, and 
it is here that the food materials held in solution are 
given up to the living parts of the body. Every part 
of the body is filled with capillaries, and through them 
each part gets its share of food from the blood. 

We must remember that the blood, whether in the 



88 



PHYSIOLOGY AND HYGIENE 



arteries, or in the veins, or in the tiny capillaries, is 
always flowing in closed tubes. It never empties into 
the tissues, but passes to them .through the delicate 
walls of the capillaries. Only ,the liquid part passes 
through, the corpuscles remaining in the blood vessels. 
Veins. — A four- track railroad usually has two 
tracks for the trains, say from Chicago, and two for 

the trains going to 
Chicago. Let us say 
that the two tracks 
from the railroad 
center represent the 
arteries which take 
the blood away from 
the heart. After its 
journey through 
smaller arteries or 
branch roads, and 
through the capil- 
Showing their method of branching. The l aY { es or switches 
figure on the right shows capillaries in 
the skin ; on the left, capillaries in the where it leaves the 

muscles - food, the blood is 

ready to go back to the heart on the return tracks. 

The little capillary branches combine into larger 
tubes or blood vessels called veins, which carry the 
blood back to the heart. The veins in turn combine, 
and the nearer they get to the heart the larger and the 
fewer in number they become. Finally they unite into 
two large veins, which pour all the blood back into the 
heart. Figure 22 B shows the connection of the heart 




Eig. 25. — Capillaeies. 



CIRCULATION 



89 



Polm> 

Grcuhtii 



m/ktion 



with these veins. With the next beat after the blood 
has been poured into the heart from the veins, it is 
pumped out again, and sent once more on its circuit to 
the lungs and around the 
body. The general arrange- 
ment of the heart, arteries, 
capillaries, and veins may be 
understood from Figure 26. 

The whole process of cir- 
culation, as it is called, is 
like what would happen if 
all the water that flows from 
our water faucets, and, after 
being used, is thrown into 
our sinks, were carried back 
to the reservoirs, there to 
be thoroughly purified, and 
sent out once more to the 
various houses. 

All of the arteries, except 
those going to the lungs, 

carry pure blood, while the Fig. 26. — A Diagram showing 
veins, except those coming 
from the lungs, carry im- 
pure blood. The pure blood 

becomes impure as it takes up waste material in the 
capillaries, as explained in a later chapter. 

The arteries are embedded deeply in the flesh ; the 
veins are nearer the surface. A cut in the flesh is 
almost sure to sever one or more small veins, but 




Capillaries 



the General Circulation. 

The blood flows in the direction 

of the arrows. 



90 PHYSIOLOGY AND HYGIENE 

unless it is very deep the arteries will not be injured. 
The blue lines appearing on the back of the hand, 
when the hand is allowed to hang downward, show 
the positions of the veins. 

HOW THE BLOOD FLOWS 

Most of us are familiar with some form of pump. 
We have noticed that the water flows out of the spout 
in spurts ; but if it is allowed to pass for some distance 
through a trough or along the ground, it flows as 
steadily as if it had come from the pump in a contin- 
uous stream. The movement of the blood in our 
bodies is similar. The heart sends the blood into 
the main artery in spurts, pumping it with force, just 
as the pump forces water into the trough. As the 
blood goes farther and farther from the heart, it flows 
along more quietly, until, by the time it has passed 
through the capillaries and is on the home trip through 
the veins, the spurting has ceased entirely. 

When the heart beats, it forces more blood into the 
arteries than can easily flow through them. Instead of 
being stiff, however, like iron water pipes, the arteries 
are elastic like India rubber. The blood flowing into 
them in spurts causes the arteries to stretch, so that 
it flows more smoothly than it would if flowing in 
similar spurts through iron pipes. 

Bleeding. — The blood is pumped into the arteries 
with so much force that it flows out very rapidly in 
strong jets if an artery is cut or broken. The bleed- 
ing must be stopped quickly, or the person may bleed 



CIRCULATION 



91 



Artery 



to death. The veins, on the other hand, do not become 
stretched, since the blood flows in them with less force. 
If a vein is cut, the bleeding is not so rapid as from a 
severed artery, and it is not so dangerous. But in 
any case the bleeding must be stopped, for even a 
small wound in a vein would cause death if the flow 

of blood were 

not checked. 
Many of the 

most common 

accidents to 

which we are 

liable produce 

bleeding. If the 

wound is only a 

slight break or 

a cut in the 

skin, the bleed- 
ing will not be 

serious. We 
only to 

bring the edges 

together and 
bind the cut or other wound some- 
what tightly with a cloth or a bit 
of adhesive plaster, and the bleed- 
ing soon stops. Even wounds which are comparatively 
deep will usually stop bleeding, if they are tightly 
bound and held quiet for a time. 
Bleeding from Arteries. — An artery wound is more 





Fig. 27. — Showing need 
the Main Artery 
of the Arm. 



Fig. 28. — Showing 
the Main Artery 
in the Leg. 

In front of the leg 
above the knee, but 
behind it below the 
knee. 



92 



PHYSIOLOGY AND HYGIENE 



serious, and must be treated promptly in order to save 
the person's life. If a cut or wound of any sort is 
followed by a forcible spurting of blood, it is certain 
that an artery has been cut. The only way to stop the 
bleeding is to compress the artery above the cut, that 
is, between the cut and the heart. Severed arteries are 
most common in the arms and the legs, and the treat- 
ment in such cases is simple. Figures 27 and 28 
show the course of the chief arteries 
in the arm and the leg. Figure 29 
shows a simple method of grasping 
the arm so as to compress the artery 
and stop the bleeding, temporarily, 
anywhere in the arm below the 
elbow. 

The easiest and most effectual 
method of stopping the flow is, 
however, to put a bandage or liga- 
ture around the arm above the cut, 
and to place a stick inside it, as 
indicated in Figure 30. The stick 
is then to be turned, twisting the 
bandage, and binding the arm 
more and more tightly, unxil the bleeding stops. 
If a stone or a tightly rolled handkerchief is placed 
under the ligature and over the artery, less pressure is 
required. A physician must then be summoned as soon 
as possible. The ligature must be kept in position 
until the physician can tie the artery and prevent 
further bleeding. With a wound in the leg the 




Fig. 29. — Showing 
how to compress 
the Arm TO STOP 
Bleeding. 



CIRCULATION 



93 



method of stopping the flow of blood is similar. 
Prompt action is of supreme importance in all such cases. 
Why the Bleeding stops. — If there is a break in the 
water pipe laid along a city street, the water continues 
to flow out until the workmen have repaired the pipe. 
The leaking would never stop 
of itself. How is it then that 
bleeding from a vein stops 
itself, or can be stopped, so 
readily ? If, whenever there 
was a break in the pipes, the 
water should freeze a short 
distance above the break, the 
ice would close up the open- 
ing and stop the leak. Some- 
thing of this sort really occurs 
in the case of a wound. The 
blood does not freeze, of 
course, but it becomes some- 
what solid ; a change takes Fig. 30. — Showing thb 
~i ~~ *~ -4- „"u-^ ,, ~ ~„n Method of applying a 

place in it which we call LlGATUEE< 
clotting. 

Blood Clotting. — Blood, as we know, is a liquid. If 
blood be drawn into a small dish, it will at first be 
liquid, like water. But if it is allowed to stand for a 
few minutes, it stiffens, becoming somewhat jellylike. 
The hardening continues until the blood is changed into 
such a firm jelly that it will not flow out, even if 
the dish is turned upside down. In other words, the 
blood has clotted, as is shown in Figure 31. A great 




94 



PHYSIOLOGY AND HYGIENE 



change has been produced in the nature of the blood, 
and after clotting it would naturally be of no further 
use, as it could no longer flow through the blood vessels. 
If blood is taken out of the blood vessels, it always 
clots in a very few minutes, no matter whether it 
is heated or cooled, or whether it is brought in con- 
tact with the air or not. So long as it remains inside 




Fig. 31. — Showing the Clotting of Blood. 
At A it is liquid ; at B it is solid. At C it is partly liquid again. 



the blood vessels it continues in liquid form. If, how- 
ever, the blood vessels themselves are injured by a cut 
or bruise, the blood begins to clot rapidly near the 
wound. 

From this fact we learn how bleeding is stopped. 
Whenever a bruise or a cut breaks a blood vessel, 
the wound at once begins to bleed. But the injury to 
the blood vessel causes a clotting in the blood near the 
bruise, and the clot soon closes the wound. As a result, 



CIRCULATION 95 

any ordinary wound soon ceases to bleed; but if there is 
a large cut through a vein or an artery, the blood may 
flow out so rapidly that it does not have time to clot. 
In such cases the bleeding must be stopped by a ligature 
or some other artificial means. 

Effect of Gravity. — If we hold the hand downward 
for a few minutes, it becomes red, because it is filled 
with blood. If, on the contrary, the hand is held 
above the head, it turns whiter. This shows us that 
the blood flows down more easily than it flows up. 
Of course, the blood in flowing through the blood ves- 
sels, is pushed on by the force of the heart. Even 
when the blood flows downwards into the legs, it must 
be pushed by the beating heart. But the weight of 
the blood itself has some influence upon its flow, helping 
the heart to send the blood down, and holding back, 
more or less, the upward flow. The aiding and checking 
of the flow by the weight of the blood, or gravity, is, 
however, of no practical importance except under cer- 
tain conditions, such as fainting. 

Fainting. — Fainting is commonly due to lack of suffi- 
cient blood in the brain. This causes unconsciousness. 
Recovery from the fainting fit occurs as soon as the 
necessary amount of blood is restored to the brain. 
When a person faints it usually means that the heart 
is not beating vigorously enough to force the blood 
upward to the brain. We should, accordingly, assist 
the heart by placing the head of the patient a little 
lower than the body. This will help the blood to run 
into the head from its own weight. The return of blood 



96 PHYSIOLOGY AND HYGIENE 

to the brain may also be hastened by stimulating the 
action of the heart. Dashing a little cold water upon 
the face hastens the beating of the heart, helps to re- 
store the blood to the brain, and so insures recovery 
from the fainting fit. Our natural impulse, when a 
person faints, is to lift his head, but as a rule this will 
hinder recovery. 

HOW THE FLOW OF BLOOD IS CONTROLLED 

Regulation of the Heart Beat. — The circulation of the 
blood is produced by the beating of the heart, and at 
the same time the heart is partly controlled by the 
brain. The heart can be entirely removed from the 
body of a cat or a dog and yet it will continue to beat, 
sometimes for hours. This shows that the heart is 
able to beat independently of the brain. Nevertheless 
the brain has the power of hastening and checking the 
heart's action. The brain is, in fact, the central organ of 
the body, and as such it controls the action of every part. 

Passing from the brain to the heart are two nerves 
which serve, like telegraph wires, to connect the two. 
Over these nerves the brain is constantly sending mes- 
sages to the heart. Sometimes the heart beats more 
rapidly than is necessary, and the brain sends a message 
which checks its action a little and makes it beat more 
slowly. At other times the heart does not beat fast 
enough, and needs to be hastened. If a boy starts 
to run, he needs to have an extra amount of blood 
sent to the muscles. Immediately a message is sent 
from the brain that sets the heart to beating faster, 



CIRCULATION 97 

which, of course, causes the blood to flow more rapidly. 
After the boy stops running, another message causes 
the heart beat to become gradually slower until it 
reaches the ordinary rate. There are many other 
occasions when a quickened heart beat is desirable. 

In every case of need responses come from the brain, 
and the heart is accordingly controlled. All this is 
done without our being conscious of it. We cannot by 
will power change the rate of the heart's beating, and 
usually we do not even know when a change occurs. 

We can readily test the difference in the rate of the 
beating by counting the number of beats a minute, 

(1) after we have been sitting quietly for some time, 

(2) after we have walked up a flight of stairs or have 
run for some distance, and again (3) after fifteen min- 
utes of quiet. 

Regulation of the Blood Vessels. — The flow of water 
from the city water pipes is regulated in two ways. 
The pump may work more or less rapidly as occasion 
demands ; the faster its movement, the greater the 
amount of water flowing into the pipes. This action 
corresponds to the changes in the rate of the heart beat. 
The flow of water in the various houses depends upon 
how wide we open the faucet, whether to its full extent, 
halfway, or not at all. So in our bodies there is a 
means of changing the size of each little blood vessel, to 
allow either more or less of the blood to pass through. 

All of the small arteries have muscle fibers running 
around them, as indicated in Figure 32. When these 
muscle fibers contract, they narrow the blood vessel, 



98 



PHYSIOLOGY AND HYGIENE 




Fig. 



32. — Section of an Artery and 
a Vein. 



Showing the thick elastic wall of the 
artery and the thinner wall of the /ein. 



lessening the amount of blood allowed to pass. When 
they relax again, the blood vessel opens and the blood 

flows in a larger 
stream. These mus- 
cle fibers are all con- 
nected with the brain, 
or the spinal cord, by 
nerves through which 
they can be made to 
relax or contract. In 
this way the flow of 
blood in any organ of 
the body can be in- 
creased or decreased. 
If for any reason a particular part of the body needs 
more blood than usual, it is not always necessary to 
increase the rate of the heart beat. The little muscles 
around the arteries simply relax, so that these blood 
vessels become larger, and at once more blood flows 
through them. On the other hand, if less blood is 
needed in a certain organ, the brain causes the muscle 
fibers to contract, so as to close, or partly close, the 
blood vessels. 

When any part of the body is actively at work, it 
needs plenty of blood, since the blood brings it nourish- 
ment. The more vigorous the work, the greater is the 
amount of blood needed. The brain needs an extra sup- 
ply when we think hard, the leg muscles when we run. 
After a hearty dinner the stomach and the intestines 
need a large amount of blood for the work of digestion. 



CIRCULATION 99 

By means of the nerves from the brain (vaso-motor 
nerves, they are called), the small arteries in the intes- 
tines are made to relax and allow the blood to flow 
through more quickly than usual. The walls of the 
intestines and the stomach become filled with blood, 
and digestion goes on rapidly. 

This large flow through the intestines necessarily 
draws some blood from the brain and othe? parts of 
the body. Accordingly, after a heavy meal most people 
are a little stupid and rather inclined to sleep. On 
the other hand, when a person is studying very hard, 
so that the brain is especially active, the blood vessels 
in the brain itself are relaxed to allow of a large flow 
of blood. It is therefore difficult to do profitable 
studying and to digest a heavy meal at the same time. 
Either the brain will take too much blood to allow of 
good digestion, or else the stomach and the intestines 
will have so large a share of the blood that tke brain is 
sluggish and the lessons suffer. 

Blushing results from a similar action of the blood 
vessels in the skin of the face ; these vessels are relaxed, 
and allow an extra amount of blood to flow through 
them. The cheeks become thereby red and warm. On 
the other hand, an unusual contraction of the vessels 
in the face causes the skin to become pale. A flushed 
skin thus means expanded blood vessels, while a pale or 
white skin means contracted ones. 

The Feeling of Warmth and Cold. — The expansion 
and contraction of the small arteries in the skin cause 
our feelings of heat and cold. The blood is warmer in 



100 PHYSIOLOGY AND HYGIENE 

the interior of the body than at the surface, but since 
only the skin feels warm or cold, we do not notice 
the warmth of the blood as long as it is below the skin. 
When we exercise vigorously, as in running, we feel 
very warm. The reason is that the exercise causes the 
blood vessels in the skin to expand so that an extra 
large amount of blood flows through them. The skin 
becomes red and the blood so warms it that we feel 
the heat. 

Although we feel especially warm when the blood 
flows rapidly through the skin, the body is in fact no 
warmer than usual. Indeed, the sending of the warm 
blood through the skin is the means by which the body 
cools its blood, to keep us from really becoming warmer. 
If the body seems likely to become too warm, it sends 
blood to the skin at once, to be cooled by the air. But 
if the body has too little heat, the blood vessels con- 
tract, and the warm blood is kept away from the sur- 
face, causing pallor of the skin. The skin blood vessels 
thus serve much the same purpose as little windows, 
which are opened or closed to regulate the temperature. 

Sometimes we are deceived by the feeling of warmth. 
Whenever the blood vessels in the skin are opened wider 
than usual, so that warm blood flows through them, we 
may be sure we are cooling off, no matter how warm we 
feel. Now there are certain substances which, if taken 
into the stomach, cause the blood vessels to enlarge. 
For example, a certain amount of alcohol causes the 
skin to become flushed and the body to feel warm. 
Many people believe, therefore, that the alcohol has 



CIRCULATION 101 

actually warmed them, and so they take it on a cold 
day to keep them warm. Exactly the opposite is the 
case. The alcoliol has caused the blood vessels to 
expand, or, in other words, it has opened the windows 
in the skin, and the body has begun to cool. The 
person feels warm simply because the skin is heated, 
but he is really losing heat more rapidly than before. 
Arctic explorers find that they cannot endure the 
extreme cold so well if they use alcoholic drinks. 

In very cold weather the use of alcohol would only 
make us colder if we were going out of doors immedi- 
ately afterwards. Sometimes when a person has been 
overcome with cold and is half frozen, and perhaps un- 
conscious from the exposure, alcohol is given to quicken 
the heart action temporarily and to hasten recovery. 
Under such circumstances it is not used to warm the 
person, but as a drug to meet an emergency. 

SUMMARY OF THE CIRCULATION PROCESS 

Let us trace briefly once more the journey made by 
the blood, beginning when it enters the heart after a 
journey around the body. It enters the right auricle 
and ventricle of the heart through large veins coming 
from the head and body. Then it is forced into the 
pulmonary artery, which carries it to the lungs to be 
purified. From the lungs it returns to the heart, this 
time entering the left auricle and ventricle, from which 
it passes into the main artery of the body. The main 
artery divides into branches which take blood to the 
head, the limbs, and the various organs; and the 



102 PHYSIOLOGY AND HYGIENE 

branches subdivide into smaller and smaller branches 
which finally end in the little tubes called capillaries. 
There the pure blood gives up its food, and at the same 
time takes up the waste products. 

From the capillaries the impure blood enters small 
veins which connect with larger veins, and these with 
still larger ones, until finally all unite in the two 
large veins which carry the blood to the heart once 
more. 

The beating of the heart is continuous, but the rate 
can be increased or diminished through the action of cer- 
tain centers of the brain ; blood supply of any organ can 
be increased or diminished by the expansion or contrac- 
tion of the small blood vessels. The whole circulation 
is controlled without our being conscious of the fact or 
being able voluntarily to change it in any way. 

QUESTIONS 

1. What is the purpose of circulation ? 

2. Describe the red blood corpuscles. 

3. What is the use of the white blood corpuscles? 

4. What is the duty of the heart ? 

5. What are arteries ? Veins ? 

6. Do any of the arteries carry impure blood ? 

7. How can we tell when an artery is cut? What should be 
done in such case ? Why is such a cut more serious than a cut 
vein? 

8. How does nature stop bleeding from wounds? 

9. If the blood would not clot, what would happen when a per- 
son is cut ? 

10. What is the pulse ? Why does a physician count a patient's 
pulse ? 



CIRCULATION 103 

11. What are the capillaries ? 

12. What is fainting? What is the remedy for it? 

13. How is the flow of blood regulated ? 

14. How is the amount of blood that each organ receives regu- 
lated? 

15. Why should we not study immediately after a hearty dinner ? 

16. If a person should run rapidly immediately after dinner, 
would it help or hinder digestion? Why? 

17. Why do we feel warm after running ? 

18. Why is it that alcohol makes a cold man feel warmer ? Is 
he actually warmer? m ' 



CHAPTER V 
RESPIRATION 

Only as the fuel in a locomotive is burned does it 
drive the engine. The burning of the fuel is really a 
union of the coal with a certain part of the air called 
oxygen. The process is oxidation, and it produces heat. 
As a result of the burning, a large amount of another 
gas, carbon dioxide, is produced, which passes out of 
the smoke-stack with the smoke, and there is left 
in the grate a quantity of ashes. In order that the 
fires in the engine may be kept burning brightly, it is 
necessary that there be a supply of air. This is fur- 
nished by means of the draft. It is necessary also 
that the gases have some means of passing off, as they 
do through the smoke-stack. The ashes must also be 
frequently removed from the grate to keep the fires 
free, and allow the air to reach the burning coal. 

The processes which take place in our bodies are 
somewhat similar to those in the engine. The food is 
oxidized, although the process differs much from the 
burning of coal, and a certain amount of heat is pro- 
duced which warms the body. Oxygen gas from 
the air is as necessary for the body oxidation as for 
burning the coal. What is more, there is produced in 
the body the same kind of gas as in the engine, carbon 

104 



RESPIRATION 105 

dioxide, and a certain material is left that corresponds 
in a way to the ashes, and of this the body must dis- 
pose. How the body gets its oxygen, and gets rid of 
its carbon dioxide, is a story in itself. This exchange 
of gases between the air and the blood is brought about 
by breathing, or respiration. 

THE AIR PASSAGES AND THE LUNGS 

When we breathe properly, air is taken in at the nos- 
trils, and after passing through the large nasal cavities 
above the mouth enters the throat. The nostrils, as we 
saw in Figure 12, lead directly to the throat, so that the 
air has a free passage. We have seen, too, that the 
mouth also leads directly to the throat. If the mouth 
is open, air may be taken through it even more easily 
than through the nostrils. In either case the air passes 
directly into the throat, and then down to the lungs. 

Mouth-breathing is not, however, the natural method 
of taking in air, and is always injurious if continued 
for any length of time. The air passes much more 
rapidly through the mouth than through the nostrils, 
and consequently it is not so thoroughly warmed when 
it reaches the lungs. What is more, the dust in the air 
is not so completely removed as when it passes through 
the nostrils. The narrow, irregular passages of the 
nose, with their moist surfaces and hairs, hold the dust 
and prevent it from passing into the lungs. We should 
carefully avoid getting into the habit of breathing 
through the mouth, even when walking fast or when 
running, lest we cause throat and lung troubles that 



106 PHYSIOLOGY AND HYGIENE 

may be a serious menace to health. If a person should 
find that he really is unable to breathe excepting with 
the mouth open, it indicates that something is wrong 
in his throat or nose, and he should be examined by a 
physician. 

The Windpipe or Trachea. — The air passes from the 
throat into the windpipe (see Fig. 12). This is a large 
tube at the front of the neck. As we have seen, it is 
always open, except that at the instant when food 
is being swallowed the epiglottis closes down over 
it like a lid. The epiglottis springs up again, how- 
ever, as soon as the food has slipped by, to allow the 
free passage of air to and from the tube. The wind- 
pipe itself is held open by a series of hard, cartilage 
rings in its walls, which prevent it from collapsing. 

Just within the upper end of the windpipe is situated 
a very important organ, the larynx. If we place our 
fingers upon the outside of the throat just below the 
jaw, we can feel a hard bunch move up and down as we 
swallow. This bunch, sometimes called the Adam's 
apple, is the larynx. Figure 33 shows its location at 
the beginning of the windpipe. Inside of the larynx 
are the so-called vocal cords, by means of which we are 
able to make sound when talking. Below the larynx 
the windpipe passes . down through the neck in a 
straight line and enters the chest, where, as shown in 
Figure 33, it divides into two branches. 

The Lungs. — When the windpipe divides, one branch 
enters one of the lungs, and the other branch enters the 
other lung. The lungs look like two elastic bags, as 



RESPIRATION 



107 



indicated in Figure 33, and are capable of being dis- 
tended when air is drawn in, and of collapsing when 
the air is expelled. Each of the bags seems to be filled 
with a mass of spongy material, which is made up prin- 



..Larynx 



Air 




Fig. 33. — The Lungs. 

Upon the left is shown the lung from the outside ; 
upon the right the lung is opened to show the 
branches of the air tubes. 

cipally of air tubes, air cells, and blood vessels. Each 
branch of the windpipe, on entering the lung, divides 
into numerous smaller branches. Each of these divides 




108 PHYSIOLOGY AND HYGIENE 

again, and so the division continues, until finally the 

smallest of the branches form a system of very minute 

tubes similar in its irregular divisions to the twigs of a 

tree. The whole lung, in fact, appears somewhat like 

a tree with the branches upside down. Each twig ends 

in a small rounded sac or air chamber. The air taken 

in through the nostrils finally enters and expands these 

little chambers, which are shown in 

Figures 33 and 34. The lungs 

contain many thousands of the 

sacs, and every time we breathe 

they expand with the air which 

they take in. Thus the whole lung, 

\AirSac$ being filled with air, is light and 

Fig. 34. —Air Sacs, spongy. It is an excellent plan 

Found at the ends of the to ^raw several long breaths every 
air tubes in the lungs. _ . 

little while, to distend the air sacs 

as much as possible, thus "clearing the lungs" as 

we say. 

Blood Vessels of the Lungs. — We have already learned 

that the right side of the heart receives the impure 

blood and sends it through the pulmonary artery to the 

lungs. When this artery enters the lungs it divides 

and subdivides into small blood vessels, which in turn 

divide into very small capillaries. The capillaries are 

wrapped around the air sacs, appearing like a sort of 

net about them (Fig. 35). While the blood from 

the heart is flowing through the capillaries it is very 

close to the air which fills the sacs. It is so close, in 

fact, that it takes some of the oxygen out of the sacs, 



RESPIRATION 



109 



giving up to them in exchange the impure gases which 
it holds. After leaving these gases and taking the 
oxygen, the blood is purified and ready to go back to 
the heart. 



HOW AIR IS DRAWN INTO THE LUNGS 

When the handles of a pair of bellows are extended 
the cavity inside is enlarged, and air is sucked in to fill 
the increased space. 
If a rubber ball with 
a hole in it is com- 
pressed until it col- 
lapses, and is then 
held in a dish of 
water and allowed 
to take its normal 
shape, the hollow 
fills with water. 
Breathing is based 
upon a similar prin- 
ciple. The air is 
forced into the 
lungs in much the 

same way that bellows are filled with air and the ball 
is filled with water. 

The Chest or Thorax. — The lungs are inclosed in a 
box called the chest. This is closed in front, at the 
sides, and at the top by the ribs, muscles, and skin. 
Figure 37 shows the chest and the position of the lungs. 
At the rear the chest is closed by the backbone and 




Fig. 37. — Showing the Chest with thb 
Lungs and Heart in Position behind 
the Ribs. 



110 



PHYSIOLOGY AND HYGIENE 



the ribs. A thin muscular partition, the diaphragm, 
stretches across the bottom, shutting the box up com- 
pletely. The windpipe is the only opening in the chest 
for the entrance of air. 

The position which the diaphragm would take if left 
to itself is that of a slight upward curve, as shown in 

Figure 38. Each time we 
draw in a breath, the muscles 
of the diaphragm shorten and 
draw it down to the posi- 
tion shown by the dotted line 
in Figure 38. This enlarges 
the space in the chest, and 
the outside air, rushing in 
through the nostrils and the 
windpipe, enters the lungs, 
and fills the enlarged space. 

The diaphragm is helped 
by the ribs in making the 
space within the chest larger. 
The ribs, in their usual posi- 
tion, tend to bend downward. 
As we breathe, the numerous 
muscles surrounding the ribs 
Fig. 38. — Showing the Move- raise them upward and f or- 
ment of the Diaphbagm in wa rd, increasing considerably 

Th^^Ztoe represents the the space within. The dotted 
position at the end of an lines in Figure 39 show the 
inhalation. position of the ribs when the 

lungs are full. Air is drawn in when we breathe ; 




RESPIRATION 



111 



when the cavity of the chest is enlarged, the pressure 
of the air forces it in to fill the enlarged cavity, much 
as air is forced into a pair of bellows. 

After the lungs are thus filled with air, the muscles 
relax, and the ribs fall of their own weight into the 
position shown in the solid 
lines of Figure 39. At the 
same time the diaphragm re- 
laxes, and is pushed up to 
its former position. This is 
chiefly accomplished by the 
pressure of the organs below, 
which it had compressed. Both 
motions decrease the size of 
the chest cavity, and the air 
is squeezed out exactly as 
the air is forced from the bel- 
lows by the pressure on the 
handles. Drawing the air into 
the lungs is called inspiration 
or inhalation. Forcing the air 
out by contraction is called 
expiration or exhalation. The 
whole process is controlled 
through nerves by the brain. 

Capacity of the Lungs. — A 
certain amount of air is 
drawn into the lungs with each 

breath, and about the same amount forced out. But 
the lungs are never completely filled by an ordinary 




Fig. 39. — Showing the 
Movement of the Ribs 
in Breathing. 



112 PHYSIOLOGY AND HYGIENE 

breath, nor are they ever completely emptied after the 
exhalation. After taking an ordinary breath we can 
still breathe in more air by an additional deep breath, 
and after an ordinary exhalation we can expel more air 
by an effort. Thus in ordinary breathing we change 
only a part of the air in the lungs. In fact, the lungs 
of a grown person commonly hold about 350 cubic 
inches of air, of which only about 30 inches are changed 
with each ordinary quiet breath. We might renew 
most of the air by very rapid and very deep breathing, 
but to do so continuously would be too great an effort. 

Lung Exercise. — The lungs should by all means be 
completely filled with pare air occasionally. If the air 
in the little air sacs is seldom changed, but remains 
more or less stagnant, the sacs furnish excellent lodg- 
ing places for dangerous bacteria, and they may even 
be the starting point for consumption, pneumonia, or 
some other lung disease. If people exercised the air 
sacs more vigorously, filling them constantly with fresh 
air, the danger of lung trouble would be decreased. 

How shall we give our lungs the needed exercise ? By 
drawing long, deep breaths, filling the lungs as full as 
possible, and then blowing out the air slowly and forci- 
bly. If we acquire a habit of frequently filling the lungs 
deeply with fresh out-of-door air, we shall strengthen 
them, increase their capacity, and improve our general 
health. Persons whose work is such as to produce vig- 
orous activity of the lungs do not need such special 
exercise. If one is obliged to walk up a steep hill 
daily, so that he becomes somewhat breathless, the lungs 



RESPIRATION 113 

receive all the exercise needed to keep thern properly 
active. The active boy or girl ordinarily gets plenty 
of lung exercise in play. It is important to remember, 
however, that with the quiet life which many persons 
live, especially in our cities, the lungs need special 
exercise to make them strong and to give them the 
amount of fresh air necessary for health. 

WHAT BREATHING DOES FOR THE BLOOD 

How Blood is changed in the Lungs. — The blood 
which enters the lungs to be purified is very different 
from the blood which returns from the lungs to the 
heart. Four important changes occur in the lungs. 

1. The blood takes up oxygen from the air. — The red 
corpuscles have the power of taking up oxygen from 
the air. Each one of the millions of these corpuscles 
takes from the air in the lungs as much of the oxygen 
as it can hold. As soon as the oxygen has been 
absorbed, the corpuscle becomes a brighter red than 
before, and consequently the blood itself is of a more 
brilliant color. The blood that flows into the lungs is 
bluish red ; the blood that comes out is bright scarlet. 

2. The blood gives up carbon dioxide gas. — The car- 
bon dioxide gas leaves the blood, enters the air in the 
lungs, and is then expelled in the exhalation. 

3. The blood is cooled. — The blood is somewhat 
cooled while it is flowing through the lungs. The air 
which we breathe into our lungs is usually cooler than 
the body. In an ordinary schoolroom it is about 70°. 
But the same air when expelled from the lungs is nearly 



114 PHYSIOLOGY AND HYGIENE 

as warm as the body (about 98°). It has been warmed 
in the lungs by the blood, the blood itself being cooled 
at the same time. 

4. The blood loses some of its water in the lungs. — If 
we breathe upon a cold windowpane, little drops of 
water collect, making the glass cloudy. These drops 
condense from the moisture we exhale. The air 
breathed from the lungs is usually nearly saturated 
with vapor. When we walk out of doors on a cold 
winter's morning, we can "see our breath"; that is, 
the water in the breath condenses into a slight fog 
as it comes from the mouth or nostrils. This water all 
comes from the blood. Thus the blood on leaving the 
lungs contains less water than when it enters. 

How the Oxygen is Used. — After the blood has taken 
the oxygen from the air in the lungs, it goes directly to 
the left side of the heart. From there, as we have 
already learned, it is sent to all parts of the body 
through the arteries, finally reaching the capillaries. 
The blood flows through the capillaries very slowly, 
and here each red corpuscle lets go of the oxygen it 
took while in the lungs. The oxygen passes at once 
from the blood to the tissues of the body around the 
capillaries. The red corpuscles are thus the oxygen 
carriers. They go to the lungs, seize the oxygen, and 
then carry it to every part of the body needing it. 
After they have given up the oxygen they become 
bluish red, so that the blood which leaves the capil- 
laries to go back through the veins to the heart is a dark 
bluish red. 



RESPIRATION 115 

We have already seen that the oxygen is brought 
into the body to unite with the food, just as it unites 
with the fuel in a locomotive, and that as a result 
there is produced the waste gas, carbon dioxide. 
While the blood is passing through the capillaries, it 
not only gives up oxygen to the tissues but it takes 
from them the carbon dioxide which has been pro- 
duced. Thus when it comes back from the tissues to 
the heart, the blood is carrying carbon dioxide in the 
place of the oxygen. Such blood is called venous blood, 
and is said to be impure because it contains waste prod- 
ucts. When this blood reaches the lungs again it gives 
off the waste carbon dioxide it is carrying and gets 
another load of oxygen. 

Respiration is then an exchange of gases between the 
body and the air. The blood is all the time passing 
through the lungs where it gives up carbon dioxide, 
water, and other gaseous waste products and takes 
oxygen. Going thence to the various parts of the 
body, it supplies them with the oxygen and takes away 
the carbon dioxide. If anything hinders breathing, 
there is trouble, for the same reason that a fire will 
not burn unless there is a draft to furnish air to the 
burning coal. If breathing stops for more than a few 
minutes death follows, since the body is then unable 
to obtain oxygen or get rid of waste gas. 

Breathing and Exercise. — We can readily under- 
stand why, if we exercise vigorously, the rate and the 
depth of breathing will be increased. If an engine is 
to work rapidly, it must have a good draft, and it must 



116 PHYSIOLOGY AND HYGIENE 

burn large quantities of coal ; a large amount of ashea 
will be left, and a great deal of smoke will issue from 
its chimney. So with our bodies. If we are to work 
our muscles vigorously, we must have a large supply 
of oxygen to oxidize the necessary food, and an in- 
creased amount of waste will be produced. The blood 
must consequently flow faster than usual, both to 
furnish the oxygen and to carry off the waste. To 
accomplish this the heart begins to beat faster so as to 
increase the speed of the blood, and at the same time 
our breathing becomes more rapid, so that the rapidly 
flowing blood may be supplied with oxygen, and all 
the waste may be carried away. 

VENTILATION 

Need of Ventilation. — It is evident that we need a 
great deal of pure air. The rooms in which we live 
should be well ventilated. There are two purposes 
in ventilation : 1. To furnish us with a sufficient supply 
of oxygen; 2. To provide air that can carry off dust, 
noxious gases, and moisture. 

Anything which uses up the oxygen in a room, 
or which allows too large an amount of breathed air 
to accumulate, renders the air unwholesome. If a 
great many people are breathing the air in a room, 
or if gas or oil stoves or lamps are using up the oxygen 
and giving out carbon dioxide, the air, unless changed, 
becomes oppressive and poisonous. In such cases it is 
especially necessary to attend well to the matter of 
ventilation. 



RESPIRATION 117 

Evils of Indoor Life. — People who live in warm 
climates spend much of their time out of doors. We 
in the colder climates have formed the habit of living 
in close rooms, where we remain for hours at a time. 
In the close rooms we are often forced to breathe over 
and over the air which has already been breathed by 
ourselves or other people, and this is most unwhole- 
some. The habitual breathing of impure air is partly 
the cause of some of the lung diseases, as pneumonia 
and consumption. This does not mean that people 
living out of doors never have lung troubles ; but such 
diseases are most common among those who live in 
close rooms. City workmen, though better fed than 
country workmen, are usually less healthy. If we 
could be in the open air most of the time, we should 
avoid many of these difficulties; but since in cold 
climates this is not pleasant in winter, we must at least 
keep our rooms supplied with plenty of fresh air. 

The Need of Fresh Air. — Many people arrange their 
living rooms with a wholly mistaken idea of what is 
healthful. They seem actually afraid of fresh air. So 
careful are they to prevent drafts that they exclude 
fresh air. They think that they take cold because the 
rooms are not warm enough, or because of changes in 
temperature, so they keep the air as uniformly warm 
as possible. Probably more colds are due to over- 
heated or impure air than to drafts or cold air. We 
take cold from drafts frequently because we accustom 
ourselves to living in warm rooms. A temperature of 
from 65° to 70°, depending upon how actively we are 



118 PHYSIOLOGY AND HYGIENE 

employed at the time, is the proper temperature for 
living rooms in cold weather. 

A very large class of people consider night air 
especially dangerous, and for this reason they sleep in 
rooms closed up tightly, to prevent fresh air from 
entering. Night air is no more injurious than day 
air, except that it is likely to bring mosquitoes, which 
should be kept out of the sleeping room ; and there 
is no time when a person should be more partic- 
ular that the air is pure than when he sleeps. The 
attempt to shut out night air from sleeping rooms is a 
grave mistake, and this is true both in winter and in 
summer. Fresh air is one of nature's best remedies 
for many diseases. If we determine to make it a 
point through life to breathe plenty of wholesome, fresh 
air, we have laid a firm foundation for vigorous health. 

How Rooms are Ventilated. — More or less fresh air 
gets into the rooms of an ordinary dwelling house, no 
matter how tightly they may be closed. If a stove is 
used in a room, the fire causes a continuous draft up 
the chimney ; this draft always removes air from the 
room, and fresh air is drawn in from outside to take 
its place. The air comes in through the cracks about 
the doors and windows, through the keyholes, and more 
or less through cracks in the floors. The direction of 
the currents of air may be seen from Figure 40. When 
there are only one or two persons in a room, and the 
doors are opened frequently, sufficient fresh air is usually 
supplied from these sources. At night such ventilation 
is not enough. Unless the wind blows very hard, some 



RESPIRATION 



119 



arrangements should be made for constant change of air, 
such as opening a window at the top in such a way that 
those sleeping in the room will not feel a direct draft. 
An open fireplace, even if there be no fire in it, is an 
excellent means of ventilation, as shown in Figure 40. 

In houses heated by means of hot-air furnaces special 
devices are usually adopted for supplying fresh air. 




Fig. 40. — Ventilation. 
Showing the means by which air enters and leaves an ordinary room. 

The furnace is connected with what is called the cold 
box, which is open to the outdoor air. The air enters 
this box, passes into the furnace, is there heated, and 
then rises through the flues into the different rooms. 
All the while air is passing out of the rooms through 
cracks in the doors and windows, or rising through 
halls or ventilating flues in chimneys, which are usually 
left open in such houses. 

When houses are heated by steam radiators it is not 
so easy to keep the air pure ; for although currents of 



120 PHYSIOLOGY AND HYGIENE 

air move up and down in the room they do not readily 
pass out, and we must depend for fresh air upon flues 
and open fireplaces. The difficulty in keeping a free 
circulation of air is partly the reason why a room 
heated by steam is apt to be "stuffy." In such a room 
there should always be some special arrangement for 
the outlet and inlet of air. Sufficient movement of the 
air may be obtained by means of open fireplaces, flues 
in the chimneys, ventilators around the windows, or 
windows slightly open at top and bottom. When a 
house with many doors and windows has many of its 
rooms opening into each other, ventilating flues are not 
especially necessary. 

When a room — such as a schoolroom or a public 
hall — holds a number of persons, special means should 
be adopted for replacing impure air. Such rooms are 
usually provided with special ventilating apparatus. 

It is worth while to remember, in any case, that cold, 
fresh air, from whatever source it may come, is less 
injurious than breathing repeatedly the air of a close, 
ill- ventilated room. There is one simple test of the 
ventilation of a room: Does the air seem fresh and 
sweet as you come from the pure outside air ? 

HOW TO RESTORE RESPIRATION 

Occasionally some accident stops a person's breath- 
ing and tends to produce suffocation. For example, 
when a person is submerged in water he can no 
longer take air into his lungs. If, however, the 
drowning person can be removed from the water 



RESPIRATION 



121 



while the heart still beats, and breathing can be started 
again, his life can usually be saved. After being taken 
from the water, the patient should be placed so that the 
head is lower than the shoulders, and turned face 
downward, to allow the water to run out of the mouth 
and throat. 

The process of arti- 
ficial breathing should 
then be started. The 
patient should be placed 
on his back, with the 
head on a level with 
the body. The arms 
should be first pressed 
against the sides of the 
body, and then raised 
outward and upward 
until they meet above 
the patient's head. 
Lifting the arms in 
this way raises the 
shoulders and ribs ; the 
size of the chest is 

thus increased, and air is drawn into the lungs. It 
is important to know that the air actually passes into 
the lungs. To be sure of this, the tongue must be 
drawn forward so as to open the throat and permit the 
air to pass. After the arms have been lifted, they 
should be lowered again, while a second person, if pos- 
sible, presses the abdomen and sides of the body. The 




Fig. 41. — The Method of moving 
the Arms to produce Artificial 
Breathing. 



122 PHYSIOLOGY AND HYGIENE 

lowering of the arms and the pressure on the abdomen 
tend to force the air out by compressing the chest. 
The raising and lowering of the arms in this manner 
should be continued regularly from ten to twelve times 
a minute, and should be kept up until natural breathing 
starts. Although this work is hard, it should be kept 
up for at least two hours if normal breathing is not 
resumed earlier. 

A feather or other light object placed in front of the 
mouth will show when natural breathing begins. If 
there is any motion of the feather to indicate natural 
breathing, the movements of the arms may be stopped. 
The person should then be wrapped in warm clothing 
or in blankets, and nature will complete the restoration, 
although it will be an aid to have the extremities of 
the patient rubbed during the whole process. This 
method of restoration should be employed if a person 
becomes nearly suffocated from any cause. Persons 
have sometimes been in the water a quarter of an hour 
or even longer, and have still been brought back to 
consciousness. 

QUESTIONS 

1. What gas is necessary for oxidation? What products re- 
sult from oxidation ? 

2. Why should we keep our mouths shut except when talking 
or eating ? 

3. Where is the windpipe ? 

4. Of what use is the larynx ? 

5. Where are the lungs situated ? 

6. How does the blood get oxygen from the lungs? 

7. How is air drawn into the lungs ? 



RESPIRATION 123 

8. Could a person breathe if there were a hole through the 
chest? Why? 

9. What form the walls of the chest? 

10. How is the chest cavity made larger or smaller? 

11. If air is taken into the chest only, why does the abdomen 
swell out with each inspiration ? 

12. How much of the air in the lungs is changed at a single 
breath ? 

13. How can we exercise the lungs ? 

1-4. W x hat four things happen to the blood in the lungs ? 

15. What does the blood do with the oxygen it takes from the 
lungs ? 

16. If one should have too few red corpuscles in his blood, what 
would be the result ? 

17. What is respiration ? 

18. When you are running, can you breathe more easily 
through your mouth ? If you do, can you run farther? 

19. Why does a schoolroom need better ventilation than a com- 
mon dwelling room? 

20. What are the purposes in ventilation ? 

21. What are the evils of indoor life? 

22. How should rooms heated by stoves and furnaces be venti- 
lated? 

23. What may be done to ventilate houses heated by steam? 

24. How may natural breathing be restored when a person has 
been almost drowned? 



CHAPTER VI 

THE FRAMEWORK AND MOTION OF THE BODY 

The stomach digests food, the heart and the blood 
vessels are in constant action, the lungs never cease to 
expand and contract as long as we live. Those organs, 
then, all have a part in aiding us to accomplish the work 
that is given us to do. But with stomach, heart, and 
lungs alone we could neither step, nor speak, nor move 
in any way. We must have in addition muscles and 
bones. Of these our bodies are largely made, and it 
is to repair and renew these, as well as to render them 
of practical use, that we possess the organs about 
which we have already studied. 

THE SKELETON 

Most of the parts of our bodies are soft, and if there 
were not a hard framework to support them, we should 
be nearly as flexible as jellyfish. But inside the pli- 
able flesh we have solid bones, which serve, like the 
beams of a house, as a support for the softer parts. 
This framework of bones is called the skeleton. A 
grown person has in his body two hundred different 
bones. A child has even more, but several of the 
bones grow together later, making just two hundred. 

124 



FRAMEWORK AND. MOTION OF THE BODY 125 



Humerus 




Fig. 42. — The Human Skeleton. 



126 



PHYSIOLOGY AND HYGIENE 



The bones are of different shapes and sizes. Figure 
42 shows the framework of the body, indicating the 
position and shape of the various bones. As will be 
seen from the figure, there is in the middle of the back 
a strong support, called the backbone. It is not one 
single piece, however, but a series of small bones 

fitting snugly to- 



Sp/no/ Cord 




Spinal Cord 
Fig. 43. — Two Vertebrae in Position. 
Showing the spinal cord passing 
through them. 



gether and capable 
of being moved. If 
the back contained 
only one bone, it 
would be stiff and 
easily broken, but 
this series of small 
bones enables us to 
bend the back with- 
out danger of break- 
ing it. Each of the 
smaller bones of the 
back is called a verte- 
bra. Figure 43 shows 
Many other animals have backbones 
These include fishes, reptiles, 



two vertebrae. 

made up of vertebrae 

birds, and the four-footed animals with which we are 

familiar. All such animals are called vertebrates. 

Figure 42 shows a large, rounded box just above the 
backbone. This is the skull, which forms the head. A 
side view is given in Figure 44. The skull is one of 
the most important parts of the body, because of the 
organs it contains. In it are the brain, the eyes, the 
ears, and the organs of taste and smell. 



FRAMEWORK AND MOTION OF THE BODY 127 

The chest, as we already know, contains the heart 
and the lungs. It is nearly surrounded by curved 
bones called the ribs. These extend from the back- 
bone around to the front. The heart and the lungs 

Cranium 



Facials 
fanes) 




Occipital 



Mandible 
Fig. 44. — The Human Skull. 

are surrounded and thoroughly protected by these ribs 
and the breastbone, or sternum. 

Each of the arms and legs is made up of several bones. 
In Figure 42 these bones are named. The bones of the 
arms and legs are the longest in the body. Since they 
are the ones that must bear the heaviest strains, they 
are also the strongest bones of the body. 



128 



PHYSIOLOGY AND HYGIENE 



THE BONES 




Structure of Bone. — The different bones are of various 
shapes, but they are all so made as to have the greatest 
strength and at the same time to be comparatively light. 
For example, the long bones of the 
leg and the arm, which must bear the 
greatest strains, are hollow. Figure 
45 represents the longest bone of the 
leg, cut open lengthwise. At the 
ends the bones are spongy, but 
throughout the length of the shaft 
they are hollow. This shape gives 
the greatest possible amount of 
strength to the bone for a given 
weight of bony substance. Although 
not all the bones are hollow like those 
of the leg, still all are so built as to 
make the skeleton strong and light. 
This allows greater ease of motion 
than would be possible if the bones 
Fig.45.-Tsection were heavier,, and yet renders them 
of the Femur. sufficiently strong for the work they 
Showing the spongy mugt <j 0# 

ends and hollow _ -' , . _ _. , 

center Bone Materials. — Bones are made 

of two different materials, one of 
which is called mineral matter, the other animal mat- 
ter. The mineral matter is hard and brittle, and 
gives stiffness to the bone. If we put a bone upon 
a. hot coal fire, and allow it to stay there for half 




FRAMEWORK AND MOTION OF THE BODY 129 

an hour, it will be very much changed. Though the 
shape will be the same, the heat has made the bone 
light and very brittle, so that it can be crumbled to 
a powder in the fingers. The hot fire has burned the 
animal matter out of the bone, leaving only the mineral 
matter, which is something- like stone, and cannot be 
burned. On the other hand, if we put a small bone, 
such as a chicken bone, into a dish of dilute nitric acid 
and allow it to remain there for a day or two. the acid 
will take out all the mineral matter. Upon removing 
the bone from the acid, we shall find it unchanged in 
shape and size, but soft and flexible, so that we can 
bend it, and perhaps even tie it into a knot. What 
is left is animal matter only. 

The mineral and the animal matter are united in bone 
so as to form one substance. The animal matter gives 
strength, while the mineral matter gives hardness. 

Bones of Children. — Occasionally a child may fall 
down a flight of stairs with no ill effects save a few 
black-and-blue spots, while the same fall would be 
likely to injure a grown person seriously. The reason 
is that there is proportionately more animal matter in 
the bones of children than in those of adults, and the 
bones of children are therefore more easily bent and 
are not so brittle. In very early childhood the bones 
are made entirely of animal matter, and are conse- 
quently soft and flexible like the bone which has been 
soaked in acid. As the child grows, more and more 
of mineral matter is deposited in the bones, until finally 
they become hard and stiff. 



130 PHYSIOLOGY AND HYGIENE 

During the first few years of a child's life the bones 
are so flexible that they can be bent out of shape more 
easily than in later life. For this reason special pains 
should be taken to teach children to hold the body 
erect. A good carriage in walking can be learned by 
every one, but most easily by children. The chest 
should be held up properly, and the chin kept in, not 
thrust forward. If the chest is kept up and the 
shoulders are thrown back, the body will take the best 
position for walking and standing. When sitting we 
should take care to sit with head erect, and with the 
back against the back of the chair or bench. 

Misshapen Bones. — If the bones of a child are con- 
stantly bent in one direction, they will be deformed. 
Although it is easy for a child to stand and sit erect, it 
is equally easy to become "round-shouldered." After 
the bones have hardened it is as difficult to change the 
habits as it was easy to form them, and later in life it 
may be impossible. Any kind of dress that causes 
strong and long- continued pressure on the bones is 
likely to cause a misshapen body. 

Wearing tight shoes will deform the bones of the 
feet. Figure 46 indicates the shape of the toes of a 




Fig. 46. — The Cramped Foot. Fig. 47. — The Uncramped Foot. 

person who wears tight shoes. Figure 47 indicates the 
shape the foot takes when it is not cramped. Wrongly 



FRAMEWORK AND MOTION OF THE BODY 131 

shaped and tight shoes cause much discomfort and 
render walking difficult, besides putting the feet in 
such a condition that the person is likely to suffer from 
the effects all through life. Deformed feet may be 





Fig. 48. — An Improperly Fig. 49. — A Properly Shaped 
Shaped Shoe. Shoe. 

produced by shoes with narrow toes or with heels 
so placed as to throw the weight of the body upon the 
toes, as shown in Figure 48. A properly shaped shoe 
is shown in Figure 49. 

A habit even worse than pinching the feet is that 
of wearing tight bands round the waist, or tight cor- 
sets. This gives rise to serious deformities, affecting 
not only the bones but also the important vital organs 
of the abdomen which are pressed out of proper posi- 
tion. The leather belts sometimes worn by boys and 
young men with outing costumes, if drawn tight 
around the waist, instead of being placed over the hips, 
are almost equally bad. Good health requires that 
the body be allowed to grow as nature intended, 
unconfined by tight clothing. 



132 PHYSIOLOGY AND HYGIENE 

Habits of stooping over one's work, of leaning against 
a support instead of standing erect, of standing con- 
stantly upon one foot without bearing sufficient weight 
upon the other, of walking or sitting with stooped 
shoulders and with the head thrown forward, or of 
wearing clothing which binds the body — any of these 
habits will destroy the beauty of the form and impair 
bodily strength. Among the prime necessities for 
attractiveness in appearance is an erect manner of 
walking and sitting, without slouching. The cadets in 
the military schools owe much of their fine appearance 
to constant drills, which exercise all the muscles, and 
which keep the body erect. 

Repair of Broken Bones. — As many a boy knows 
from personal experience, bones will occasionally get 
broken in spite of the fact that they are tough and 
strong. Very fortunately, unlike broken teeth, bones 
when broken can be mended. Each bone is supplied 
with one or more tiny blood vessels, which furnish 
blood for its nourishment. The animal matter in the 
bone is alive, and so is able to grow. 

If, after a bone is broken, the two ends are brought 
nicely together, this living part of the bone begins to 
make new bony material, which grows between the 
ends, finally uniting them again as strongly as ever. 
The bone must be kept still until it is firmly knit, for 
any motion would pull the ends apart. For this rea- 
son the physician binds the broken bone tightly in 
splints. The setting of a broken bone consists simply 
in bringing the broken ends together and binding them 
in the proper position. 



FRAMEWORK AND MOTION OF THE BODY 133 

Since there is more animal matter in the bones of a 
child than in those of a grown person, broken bones 
are more easily mended in childhood. In old age the 
amount of animal matter is less, so that the bones are 
more brittle and more easily broken. They are also 
less easily repaired. 

CARTILAGE 

The framework of the body is not wholly bone. A 
part of it is made of a substance called cartilage. This 
is so soft that it can be cut with a knife. It is so 
flexible that it can be bent easily, but at the same time 
it is very tough. It is found in several places in the 
body where there is need of greater flexibility than 
bone would give. For example, the ribs are united 
with the breastbone at the front of the chest (see Fig. 
42) by little pieces of cartilage. This makes them 
slightly movable and not Cartilage 

easily broken. Little 
cushions of cartilage are 
also found between the 
vertebrae of the backbone, 
as indicated in Figure 50. 
Here they relieve the jar 
which would result from 
a jump, if the bones actu- Fig. 50. — Two Vertebra. 

ally touched each other. Showing the cartilage cushion that 
_ . separates them. 

There are pieces of carti- 
lage around the larynx, and the outer ear is made 
entirely of cartilage covered with skin. Cartilage 




134 PHYSIOLOGY AND HYGIENE 

is not easily broken, but if once severed, it does not 
mend so easily as bone. 

JOINTS 

When we consider that the framework of our 
bodies is made of two hundred separate pieces, we 
wonder how they can ever be united in a firm struc- 
ture. They are fastened as firmly as the parts of a 
house are nailed together. In some places, as in the 
skull, they are so united that they cannot be moved. 
In other places, as at the elbow and in the fingers, they 
can be turned about freely. Whenever two bones come 
together they form a joint. If it were not for our 
joints we could not move ; and when an accident injures 
a joint, we become stiff and lame. There are two 
principal kinds of joints in the body, the hinge joint 
and the ball-and-socket joint. Let us see what each is 
like. 

A Hinge Joint. — The bones forming a hinge joint can 
be moved back and forth in one direction only, like a 
door on its hinges. The joints at the knee and the 
elbow are of this character, as is also each joint of the 
finger. If we try to move the finger or the elbow, we 
find that it will move in one direction only. The hinge 
joints are all so much alike that we need to study 
only one in detail. Let us take the knee joint as an 
illustration. 

Two bones come together at the knee to form the 
joint, — the thigh bone, or femur, and the shin bone, or 
tibia, as shown in Figure 51. The ends of these bones 



FRAMEWORK AND MOTION OF THE BODY 135 

are large and rounded, and the two fit together so 
as to be very easily moved. As can be seen from 
Figure 51, these bones are so shaped that they can be 
moved back and forth, but not sidewise. The ends 




Cartilage-' 



Fibula 



Fig. 51. — The Bones forming the Knee Joint. 



of the bones, which are rounded and smooth in them- 
selves, are made still smoother by being covered with 
a layer of soft cartilage. 

To keep the parts of a bicycle in smooth running 
order we oil them. The various joints of the body 
are provided with a liquid that takes the place of oil 
in the wheel. This is the way it is arranged : the 
bones of the joint are partly surrounded by a thin 
membrane or tissue, which supplies a liquid to the joint 
between the two bones. The liquid moistens the ends 
of the bones, thus preventing friction. If it were not 
for this liquid the bones would rub against each other, 
and it would be impossible to use the joint. The 



136 



PHYSIOLOGY AND HYGIENE 



shapes of the bones themselves and their smooth ends, 
together with the liquid, allow very free motion. 

How the Bones are held together. — No matter how 
nicely two bones might be fitted together, if they were 
not well fastened in some way the slightest twist would 
put them "out of joint." As it is, a bone occasionally 

.Anterior 

]L/yament 

Femur\ 
Patella 





Capsular 
Ligament, 

Posterior 
Ligament 

Fig. 52. — The Knee Joint. 

Showing the ligaments connecting the bones. 

slips out of place, but only when there is a severe 
strain of the joint. To avoid such danger the ends of 
the bones are fastened together by two kinds of con- 
necting bands which extend from one bone to the other. 
These are ligaments and muscles. 

The ligaments are made of a white, tough, flexible sub- 
stance. Several ligaments may be seen in Figures 51 
and 52. They pass from one bone to the other across 
the joint. Some of them are placed in front, some at 
the sides, and some at the back. The ligaments are, 
however, rather loose, so that while the bones cannot 
slip out of place, they might, if they were held in no 
other way, move too freely. 



FRAMEWORK AND MOTION OF THE BODY 137 

In addition to the ligaments, therefore, the bones 
are held in position by means of certain muscles. The 
motion of the bones at the knee joint is produced by the 
muscles, all of which lie above the knee. From the 
ends of the muscles, long, slender cords or tendons pass 
down over the knee joint and are attached to the bones 
below the knee. These muscles are elastic and, being 
slightly stretched, they help to hold the bones in close 
contact. Outside of the muscles is the skin, which 
covers the bones, tendons, ligaments, and muscles, form- 
ing a protection for them all. 

We move our joints so unconsciously, as we take a 
step forward or sit down in a chair, that we hardly 
realize how complicated they really are. But when we 
consider that so complicated and well-fitted an arrange- 
ment is provided simply to enable us to move a knee, 
we cannot fail to hold these bodies of ours in great 
respect. A single hinge joint means that we have 
two smooth bones rounded just so as to fit into each 
other, strong ligaments to bind them together, muscles 
and tendons to assist in movement, and a protecting 
skin surrounding all. 

Other Hinge Joints. — The other hinge joints of the 
body are like the knee joint. In all cases the bones 
are rounded and are moistened with the liquid to pre- 
vent friction. All are held together by muscles and 
ligaments, and all are so arranged that they can be 
moved in only one direction. The joints at the elbows, 
at the wrist and ankle, and in the fingers and leg are 
all hinge joints. 



138 



PHYSIOLOGY AND HYGIENE 



A Ball-and-Socket Joint. — To show the arrangement 
of a ball-and-socket joint we will study the shoulder joint. 
In general such a joint allows the bones to move in every 
direction. We can lift the arm above the head, to the 
front, to the side, turn it around, and bend it backward 
as far as the hinge joint at the elbow will allow. The 
two bones which form the shoulder joint are the 

shoulder blade, or scapula, 
and the upper arm bone, 
or humerus. The shapes 
of these bones may be seen 
from Figure 53. 

As is evident from the 
illustration, the shoulder 
blade has a somewhat 
rounded hollow. The up- 
per end of the arm bone 
is rounded like a ball 
and fits into this socket or 
hollow. Since the end of 
the arm bone is a ball, and the socket in the shoulder 
blade is a hollow cavity, the arm can be moved in all 
directions. It is this shape of the bones that gives us 
our great freedom in lifting the arms. The ends of the 
bones are not only rounded, but they are made particu- 
larly smooth by being covered with cartilage, and they 
are also moistened with liquid like that in the hinge 
joint. 

The bones are bound together at the shoulder by just 
such strong bands as we saw at the knee. There is, 




Fig. 53. — The Bones of the 
Shoulder Joint. 




Capsular 



FRAMEWORK AND MOTION OF THE BODY 139 

however, as Figure 54 shows, only one important liga- 
ment. It is a loose, leathery sac fastened to the shoulder 
blade. From the shoulder 
blade it passes over the 
joint on all sides, and is 
attached to the upper end 
of the arm bone, so as to 
cover the joint com- 
pletely, and hold the end r Lljj. 
of the arm bone in the 
socket. If this ligament 

should be Cut, the bones Fig. 54. — The Shoulder Joint. 

could be taken apart very showing ligaments, 

easily. 

The strength of the shoulder joint is due very largely 
to the fact that it is surrounded by strong muscles. 
These muscles cover the joint on all sides, giving it 
great strength and firmness. The muscles in the 
shoulder have tendons which pass down over the joint 
and are fastened to the arm bone, thus holding it 
firmly in position. 

Other Ball-and-Socket Joints. — The only large ball- 
and-socket joints in the body, besides those at the 
shoulders, are at the hips. The hip joint allows the leg 
to be moved in various directions, but the movement is 
not quite so free as that at the shoulder. 

Injuries to Joints. — There are two kinds of injuries 
to joints which are common. They are dislocations and 
sprains. 

A bone pulled out of its place in the socket pro- 



140 PHYSIOLOGY AND HYGIENE 

duces a dislocation. If, for example, a fall or a wrench 
should pull the end of the arm bone from the hollow 
in the shoulder blade into which it fits, we say the 
shoulder is dislocated. When a bone is thus wrenched 
from its proper position it cannot be moved in the 
ordinary way. The bone must be put back in its 
normal place in the joint. This should be done by a 
physician, unless it chances to be one of the small 
bones in the finger, which almost any one can pull back 
into place by slightly pulling the bones apart and then 
slipping the dislocated bone into position. When a bone 
is dislocated, it is very likely that some of the connect- 
ing bands or ligaments may be strained or slightly torn. 
A sprain is a tear or strain in one or more of the 
ligaments of a joint. A sprain is common in con- 
nection with dislocated joints, but it occurs frequently, 
also, when there is no dislocation. A violent strain at 
any joint may cause such a pulling on the ligaments as 
to injure them and produce a sprain. The injury is 
sometimes very slight and sometimes very great. A 
sprain may be even more serious than a dislocation or a 
broken bone, requiring a longer time to heal. In case 
of a sprain, the joint should be placed in a comfortable 
position. Water, as hot as can be endured, should 
then be applied, and this should be followed by cold 
water. The joint should be bound tightly with band- 
ages. It is wise, of course, to rest the joint, but it is 
not wise to keep it perfectly still during the healing 
process, lest it be stiff for a long time. The sprain 
will be more quickly healed if, beginning say a day or 



FRAMEWORK AXD MOTION OF THE BODY 141 



two after the accident, the joint is used a little each 
day. 

THE MUSCLES 

A large part of the food we eat is used to enable us 
to move. The motions of the body are brought about 
by the muscles. The lean part of meat consists of 
muscles, and the muscles in our bodies are very similar 
in appearance to lean beef, as it comes from the market. 
The joints, ligaments, and tendons of themselves would 
be unable to move the body. It is through the muscles 
that the power is applied. 

Structure of a Muscle. — To understand the structure 
of a muscle, let us look at the one in the front part of 
the upper arm, known 
as the biceps, which we 
see represented in Fig- 
ure 55, The biceps 
muscle, as the figure 
shows, is a rather long 
mass of flesh, large in 
the middle but taper- 
ing at the two ends. 
The middle part is 
made up of reddish 
flesh, and is the mus- 
cle itself. At the ends 
firm, white bands or cords, which neither contract nor 
expand, connect the muscle with the bones. These 
are tendons or cords. 




(//no 
Fig. 55. 
Showing the method of attachment of 
the biceps muscle to move the fore- 
arm. 



142 



PHYSIOLOGY AND HYGIENE 



Most of the muscles in the body are connected with 
bones by tendons. The tendons differ in length, some 
of them being very short. A series of such cords at 
the wrist extends from the arm to the fingers, and at 
the ankle from the leg to the toes. 

If we grasp the left arm just below 
the elbow with the right hand, and 
then open and close the fingers of the 
left hand, we can feel the motion 
of the arm muscles. These muscles 
move the fingers, and are connected 
with them by the long tendons which 
pass to the finger bones. If we clinch 
the fingers of the left hand and grasp 
the wrist with the right hand, we can 
feel how tightly the tendons are 
stretched as they pass along the front 
of the wrist. Figure 56 shows their 
arrangement. 

A muscle seems to be a solid mass 
of flesh. If we examine it under a 
Showing the muscles microscope, however, we find that it is 
and tendons of the rea u v ma d e U p f an immense number 

of threads or muscle fibers, as they are 
called. We can see how the fibers are arranged, from 
Figures 57 and 58. These muscle fibers are too small 
to be seen without a microscope. They run lengthwise 
in the muscle, and they are very numerous. They are 
bound together by a thin, delicate substance which 
fastens them firmly to one another. 



FRAMEWORK AND MOTION OF THE BODY 143 



Great numbers of minute blood vessels run in and 
out among the fibers, furnishing the muscle with its 
nourishment, as shown in Figure 36, facing page 108. 
These blood vessels are the capillaries which, as we 
learned, receive the blood when it leaves the arteries, 
before its return to the heart by way of the veins. The 
walls of the capillaries are so thin that the food which is 




Fig. 57. — A Bit of Muscle. 
Slightly magnified. 



Muscle^ 
Fibers 

Fig. 58. — A Bit of Muscle. 

Highly magnified, showing muscle 
fibers. 



in the blood passes through them to the muscle fibers, 
giving them power to move and building them up. 

Involuntary Muscles. — There is another kind of 
muscle which we hear less about. These muscles are 
called involuntary muscles, because we do not consciously 
control them. The most important are those which form 
the walls of the stomach and intestines and propel the 
food, and those which contract and expand the arteries 



144 PHYSIOLOGY AND HYGIENE 

and thus regulate the flow of blood. These muscles are 
very different in appearance from the ones we have 
just described, but they also are made of microscopic 
fibers, bound together in flat masses. They are much 
more sluggish in their action than the other muscles, 
and we not only have no control over them, but we 
are not even conscious of their action. But since they 
drive the food along the intestines and control the flow 
of blood, they are of great importance. 

The Contraction of a Muscle. — If we stretch a rubber 
band, it becomes longer and thinner ; when we let go 
of the ends, it shortens and becomes as thick as before. 
In somewhat the same way the muscles of the body 
are shortened, the muscle growing thicker as it con- 
tracts. If we clinch the left fist, grasp the left arm 
above the elbow with the right hand, and then lift 
the forearm forcibly, we find that the biceps mus- 
cle becomes larger and harder as the hand is raised. 
After the arm has been lifted, the muscle may hold it 
up for a time, but to do so constant effort is required. 
The moment we relax the effort the arm falls of its 
own weight. To lift the arm the muscle must be con- 
tracted, but no muscular effort is required to lower it. 

There is, however, on the back of the arm, as shown 
in Figure 55, a muscle which acts in the opposite way 
from the biceps. If this muscle shortens or contracts, 
it pulls the arm down, stretching the biceps, as may be 
understood from Figure 55. The two muscles thus 
form a pair opposed to each other ; when one of them 
contracts, the other is lengthened. One lifts the arm 



FRAMEWORK AND MOTION OF THE BODY 145 

up, and the other straightens it. It is the contraction 
of a muscle that produces motion or action. 

What makes the Muscles contract. — In addition to 
the blood vessels in each muscle, there is connected 
with it a white cord — a nerve. This nerve is larger in 
the large muscles than in the small ones. The nerve 
is made up of nerve fibers, and each muscle fiber re- 
ceives its nerve fiber. All of these fibers are connected 
with the spinal cord, and through the spinal cord, with 
the brain. 

Why are the muscles connected with the brain? Just 
this : The nerves serve much the same purpose as 
electric wires. The muscles never contract of their 
own accord any more than an electric bell will ring 
itself. To ring the bell we must press a button. This 
sends an electric current through the wire and causes 
the bell to ring. In about the same way the muscles 
of the body act, when the proper kind of message 
comes to them. If the current, or stimulus, as it is 
called, never comes, the muscle will remain quiet for- 
ever. The stimulus is given to the muscle through 
the nerves. The brain, which is the central station 
for all kinds of action, is able to send stimuli down 
to the muscles through these thousands of little threads, 
and when the muscles get the message they contract. 
The involuntary muscles are excited into action in 
the same way, for, although we do not will to move 
them, the brain sends stimuli to them as it does to the 
other (voluntary) muscles. 

This power which the brain has over the muscles 



146 PHYSIOLOGY AND HYGIENE 

is very wonderful. Not only can the brain cause 
a single muscle to contract at any time, but it can 
cause many muscles to act together, either in connec- 
tion with one another or separately. For example, when 
a boy throws a stone, he lifts his arm, closes his fingers 
about the stone, presses one foot hard against the 
ground, and sets his body firmly to assist in the throw- 
ing ; then he must quickly contract the muscles of the 
arm and shoulder, and loosen the stone from his fingers. 
In all, from fifty to a hundred muscles must be con- 
tracted at nearly the same time. 

The boy does not realize that he is using such a 
wonderful machine, or even that he is contracting 
muscles. He simply thinks, " I will throw the stone," 
and the brain gives the proper order to the numerous 
muscles. The message must be sent to each of these 
muscles at the same time, and must cause each to 
contract just the right amount. If the brain should 
make a mistake, and cause some muscles to contract 
too much or not enough, the stone would go wide of 
the mark. This really happens many times when the 
boy is learning to throw straight. We say that " prac- 
tice makes perfect"; that is, the boy must learn how 
t& throw the stone just where he wants it to go. In 
other words, the brain must learn how to make the 
muscles work in the proper way. 

Number and Positions of the Muscles. — The fleshy 
part of our bodies is made up of a little more than 
five hundred muscles. They differ in size and shape. 
Most of them are fastened to at least two bones, so 



FRAMEWORK AND MOTION OF THE BODY 147 



that as the muscles are contracted the bones are moved. 
Figures 56 and 59 show how the muscles are arranged 
in the body, though compara- 
tively few are represented 
here. The various muscles 
are so attached to the bones 
that they can be moved in 
all the directions that the 
joints permit. We can bend 
the arm or straighten it ; we 
can move it to either side or 
turn it around, each motion 
being produced by a different 
set of muscles. 

Muscle Growth. — It is a 
peculiarity of muscles that 
the more they are used, the 
stronger they grow. The 
blacksmith, because he con- 
stantly swings his heavy 
hammer, develops very strong 
muscles in his arms. When 
a person learns to ride a 
bicycle, he finds that certain 
muscles of his legs are weak, 
but, as he continues the exer- 
cise, the muscles become 
stronger, until he can climb 
even high hills without any great strain. One set of 
muscles, however, should not be developed and others 




Fig. 59. —The Surface Mus- 
cles of the Body. 



148 PHYSIOLOGY AND HYGIENE 

neglected. The man who has all his muscles moderately 
well developed is stronger and more healthy than the 
one who has highly developed his arm muscles with- 
out exercising equally the other muscles of the body. 

If muscles are not used, they become small and 
weak. If a muscle were left idle for a few months, it 
would lose much of its power, so that we could not use 
it at all. Children in their active play ordinarily use 
all their muscles, so that they develop evenly. But 
as people grow older, certain muscles are used less and 
less. We take the trolley-car and the elevator to save 
the trouble of walking: as a result, we find that we 
cannot walk so far as we could a few years ago. We use 
the right hand in our work rather than the left, and 
the left hand is weaker and less skillful. We sit in a 
comfortable easy-chair until the muscles of the back are 
weakened, and as a result we cannot sit upright for 
any length of time without fatigue. Although we really 
want our t bodies to be well developed and vigorous, we 
get into these habits of neglecting the muscles from 
carelessness. 

Exercise. — ■ It is worth our while to make special 
efforts to use all the muscles of the body. If we find 
that certain muscles are weak, those are the ones that 
we should take pains to exercise. Too frequently we 
do the reverse. If we find something that is particularly 
hard for us to do, perhaps sweeping or sawing wood, 
that is just what we should do every day, until the 
muscles are so developed that we find it easy work. 

In large cities the chances that young people have 



FRAMEWORK AND MOTION OF THE BODY 149 

for muscular exercises are limited. For this reason 
gymnasiums have been erected in cities, and especially 
in schools and colleges. The person who commonly 
needs the most urgent advice to take exercise is the 
boy or girl who is ambitious to become a scholar. 
He prefers to spend all his time at his books, and is 
not willing to give even a little time each day to ac- 
tive exercise. He should remember that the person 
who studies all the time is likely to be outstripped 
by the one who studies and plays as well. Many 
students break down because they do not take sufficient 
exercise. 

Out-of-door games afford the best possible exercise, 
since these not only develop the muscles but give the 
player fresh air and recreation at the same time. Such 
games as baseball, golf, and tennis are excellent. Bicy- 
cling is good exercise, though " century runs " and very 
fast riding are dangerous, and the habit of bending 
over the handle bars makes one liable to what is known 
as bicyclers' stoop. Brisk walking and running are 
very good exercise ; strolling can hardly be called exer- 
cise at all, although in other ways a quiet walk in the 
open country is beneficial. 

The royal maxim for perfect body development is : 
A perfect body requires the development of all muscles ; 
all powers unused are weakened. 

So-called "Stimulants." — Some people have the mis- 
taken idea that they can increase their muscular power 
by using what are wrongly called stimulants, generally 
meaning some form of liquor. For a short time after a 



150 PHYSIOLOGY AND HYGIENE 

person has taken the alcohol there may be a slight 
increase of muscular power, but a decrease of such 
power follows very soon, so that there is in the end an 
actual loss of. power. If alcohol is used in any consid- 
erable amounts, there is a great weakening of muscular 
power. 

The use of alcohol will unfit any boy for good work 
in an athletic contest. Under no conditions does alco- 
hol enable an athlete to do his best. It has a tendency 
both to weaken the muscles and to dull the senses. 
Boys and young men sometimes make the mistake of 
trying to " brace themselves up " for a contest by the 
use of alcohol. Professional athletes know enough to 
let alcohol alone under these circumstances. 

QUESTIONS 

1. Of what is the framework of the body made ? What is 
this framework called? 

2. What organs are inclosed in the skull ? 

3. How are the long bones of the arm and leg constructed? 

4. Of what are bones made? 

5. If we did not have enough lime in our food, what effect 
would it have on the bones? 

6. How do children's bones differ from those of a grown 
person ? 

7. What happens to the bones if there is unnatural pressure 
upon them ? 

8. What are the results of wearing tight clothing ? 

9. How are broken bones repaired ? 

10. What is cartilage? Where is it found? 

11. What two kinds of joints are there in the body? 

12. How is a hinge joint made ? 



FRAMEWORK AND MOTION OF THE BODY 151 

13. Mention all of the kinds of supporting and connecting tis- 
sues found in the body. 

14. What is a ligament ? 

15. What is a tendon? 

16. How does the ball-and-socket joint differ from the hinge 
joint ? 

17. How are the bones in a ball-and-socket joint fitted and 
fastened together? 

18. Whj do we have a hinge joint at the knee instead of a ball- 
and-socket joint? 

19. Why do we need a ball-and-socket joint at the shoulder? 

20. What is meant by dislocation ? 

21. What is a sprain ? 

22. What are the parts of a muscle ? 

23. How is a muscle contracted? 

24. How is the muscle contraction controlled by the brain ? 

25. Why is it that a person falls over if he suddenly faints or 
dies, when in a sitting or standing position? 

26. What effect have exercise and lack of exercise upon the 
muscles ? 

27. What are the best kinds of exercise ? 

28. Give some examples from your own observation of loss of 
power from disuse. 

29. What is the effect of alcohol upon the muscles ? 



152 



PHYSIOLOGY AND HYGIENE 



A LIST OF THE CHIEF BONES IN THE BODY 



All forming the skull. 



J 



Forming the 
thorax. 



The nasal bones. 

The frontal bones. 

The parietal bones. 

The occipital bone. 

The mandible or lower jaw 

The sternum or breastbone. 

The ribs from the backbone to the sternum. 

The vertebrae forming the spine. 

The sacrum at the lower end of the vertebrae between the hips. 

The coccyx, a small piece of bone below the sacrum. 

The scapula or shoulder blade. 

The clavicle or collar bone. 

The humerus, from the shoulder to the elbow. 

The radius and the ulna, from the elbow to 

the wrist. 

The carpals or wrist bones, eight in number. 

The metacarpals, from the wrist to the fingers. 

The phalanges or finger bones. 

The ilium. 1 _ , „ . . _ 

T , . I Fused together to form the hip bone, or pelvic 

The ischium. J ° 

The femur, from hip to knee. 

The tibia and fibula, from knee to ankle. 

The tarsals or ankle bones. 

The metatarsals, from ankle to the toes. 

The phalanges, or bones of the toes. 



The arm. 



The leg. 



CHAPTER VII 

THE KIDNEYS AND THE SKIN AND THEIR 

DUTIES 

WASTE PRODUCTS 

Use of Food by Muscles. — A muscle is like a little 
steam engine which cannot work except when burning 
fuel. We have seen how the different foods are carried 
throughout the body by the blood. When these foods 
reach the capillaries, the muscle fibers take what they 
need for their use. The proteids serve especially to 
make new muscle tissue, which is constantly needed 
to take the place of that used up by the work of the 
muscle. The proteid or building foods are also needed 
to repair any injury that may have come to the muscle, 
and to supply the new material needed when the 
muscle is developing and growing. The sugars and 
fat, with some of the proteids, simply furnish heat and 
force ; in other words, they are fuel foods. The food 
is oxidized in the muscles by means of the oxygen 
brought by the blood. As a result, force is developed 
to enable the muscles to contract, and heat is produced 
to warm the body. 

Waste Products of Muscle Action. — When coal or 
other fuel is burned, or oxidized, smoke and gas pass 
off into the air and ashes are left in the grate. These 

153 



154 PHYSIOLOGY AND HYGIENE 

are waste products, because they are not used and can- 
not be used for heating. When the fuel food of the 
body is oxidized in the muscles and tissues, waste 
products are left, which are of no further use. These 
are carbon dioxide, water, and other substances. 
These waste products must be gotten rid of. We 
have already seen how the carbon dioxide is taken 
away by the blood, and breathed out of the body from 
the lungs. We know also that some water goes out 
in the breath. A larger quantity of water passes off 
through the skin and from the kidneys, as we shall 
see presently. The third waste product, known as 
urea, is taken from the blood by the kidneys, and 
finally leaves the body in the urine. 

A large proportion of the food we eat is taken by the 
muscles to supply muscular force. Some of it is used 
in the brain, a small amount in the glands, and certain 
quantities in every active part of the body. But, al- 
though the uses made of the food may differ in the 
various places, the same oxidation takes place, and the 
same waste products always result. 

Secretions and Excretions. — The materials produced 
by the body are generally classified under two heads. 
Those like carbon dioxide and urea are simply waste 
products and of no use at all. They are generally 
called excretions. But some of the materials are pro- 
duced for special purposes. For example, the gastric 
glands in the stomach produce gastric juice to aid 
digestion, and the salivary glands produce saliva for the 
same purpose. Materials which are thus of use to the 



KIDNEYS AND SKIN AND THEIR DUTIES 155 

body are called secretions, and they are generally pro- 
duced by special organs called glands. We have 
already learned of several of these, the salivary glands, 
the gastric glands, and the pancreas. 

The excretions are not only of no use, but if allowed 
to collect in the body they act as poisons. Hence they 
must be gotten rid of promptly. 

Some of them can pass off through the lungs in the 
breath, and some from the skin in perspiration, but 
some are disposed of in other ways. 



THE KIDNEYS 

Urea is thrown off from the body by means of a pair 
of organs called the kidneys. Each kidney is, in a grown 



Blood 
Vessel 




Fig. 60. — The Kidneys. 
The one on the right is cut open to show the tubes which secrete the 

urea. 



156 PHYSIOLOGY AND HYGIENE 

person, some four inches long and one and a half inches 
wide. The kidneys are located in the back part of the 
abdomen, just below and behind the stomach, and close 
to the backbone. Their shape is indicated in Figure 60. 
A large artery brings the blood to each kidney, as the 
same figure shows, and a large vein takes the blood 
away. There is also a tube, called the ureter, that 
passes from the kidney to the bladder, and takes away 
the material removed from the blood by the kidney. 

The kidney is made up of a large number of blood 
vessels, together with a series of small tubes, called 
kidney tubules, as shown in Figure 60. As the blood 
passes through the kidney, the tubules take the urea 
and some other solid matters which are dissolved in 
the blood. This material, together with considerable 
water, which is also taken from the blood, is poured 
into the ureters, and passes to the bladder and then out 
of the body. 

THE SKIN 

Although mainly of use as a covering for the body, 
the skin has special functions of its own. It serves as a 
means for the passing out of waste and for regulating 
the heat of the body. A healthy skin is absolutely 
necessary if the body is to be in good condition. Slug- 
gishness or improper action of the skin in its work is 
likely to cause sickness. 

Structure of the Skin. — The skin is a thick sheet like 
a close-fitting garment, covering the entire body. A 
grown person has about sixteen square feet of skin. 



KIDNEYS AND SKIN AND THEIR DUTIES 157 



Epidermis 



Dermis 



The average thickness is about one sixteenth of an 
inch, though it is thinner in some places than others. 
It is thickest on the soles of the feet and the palms of 
the hands. 

If we take a thin 
slice of skin and 
look at it through 
a microscope, we 
find that it has two 
layers, one outside 
of the other, as 
shown in Figure 61. 
The outer layer is 
called the epidermis, 
and the inner layer 
is the dermis. We 
can stick a pin 
through the epider- 
mis without feeling 
it, but the instant 
the point enters the 
dermis we feel pain. 
All the epidermis, 
except a thin layer 
on the inner side, is practically lifeless, and contains 
neither nerves nor blood vessels. The dermis is full 
of blood vessels and nerves, and is very sensitive. 

The Epidermis. — The epidermis, though lifeless at 
the outer surface, is continually growing on the inside, 
where it is in contact with the dermis. Very often 




Fig. 61. — A Section of a Bit of Skin. 
Highly magnified. 



158 PHYSIOLOGY AND HYGIENE 

when we look at our hands we can see one or more bits 
of loose skin which may be pulled off without harm. 
The outside skin is all the time being thus worn or 
rubbed off, bit by bit, and it keeps growing from the 
inside. The epidermis is so firmly attached to the 
dermis that the two are not easily separated. Occasion- 
ally we burn a spot on the ringer, or are severely sun- 
burned, so that blisters appear, that is, a little watery 
material has gathered between the epidermis and the 
dermis. If the blister is broken and the outer skin 
removed, the dermis is exposed. This is always sen- 
sitive and tender. 

Thick Parts of the Epidermis. — A boy who is an en- 
thusiastic ball-player is very proud of certain bunches on 
the palms of his hands, called callosities. The constant 
rubbing and striking of the ball causes the epidermis 
to grow more rapidly at these spots than elsewhere, and 
so it becomes thicker. Any part of the skin that has 
an extra amount of use grows thicker than the rest, this 
being nature's means of protection against injury. 

If we wear tight or poorly fitting shoes that con- 
stantly rub the toes, round bunches called corns are 
formed by the thickening of the skin. We can pre- 
vent the growth of corns by wearing shoes large 
enough not to pinch the toes, and yet snug enough 
not to chafe the feet. It is difficult to get rid of corns 
after they have once formed, so it is wise to avoid 
the great discomfort which they cause by taking proper 
care of the feet. Children who go barefooted in the 
summer rarely have either corns or deformed toes. 



KIDNEYS AND SKIN AND THEIR DUTIES 159 



Occasionally certain parts of the skin grow too thick, 
causing what are known as warts. Children are apt to 
be superstitious about these growths, because they come 
and go so suddenly. Some children believe that warts 
result from handling toads, and that they can be cured 
by the use of certain charms, both of which are absurd 
ideas. If a wart grows 
large enough to be 
really troublesome, it 
can be burned off with 
acid, but under ordi- 
nary conditions warts 
had better be let alone. 
They will disappear 
without assistance in 
time. 

Hair. — Nearly all 
parts of the skin are 
covered with hair, 
which is an outgrowth 
from the epidermis. 
Figure 62 shows that , 
each hair extends down Gn »">9 CdlS 

,-, t ., , . . ' Fig. 62. — A Hair. 

through the skin into a 

Showing its root and follicle, 
little pocket. This is 

called the hair follicle. A very small mound, or 

papilla, which is the place where the hair grows, is 

located at the bottom of the pocket. The hair is thus 

constantly growing at its root, and being thus pushed 

out of the pocket. In other words, the hair grows from 




Oil 
Gland 
hair 
Follicle 



Hair Papilla 



160 PHYSIOLOGY AND HYGIENE 

the roots, not from the ends. If a hair is pulled out, 
the little mound at the root usually keeps on sending 
out more substance, so that a new hair grows to take 
the place of the old one. If the whole follicle, includ- 
ing the mound at the bottom, is destroyed, no new hair 
will grow. 

Each hair is supplied with oil from tiny oil glands. 
These open into the follicle from the sides, as shown in 
Figure 62. They produce an oily substance that mois- 
tens the outside of the hair, keeping it soft and flexible. 
If the hair is brushed frequently, the oil will be distrib- 
uted over it, so that no hair oil need be used to keep it 
in good condition. We should never brush the hair 
with anything but a soft hairbrush. Wire brushes are 
likely to scrape the scalp so that the follicles may be 
injured, and they may pull out the hair. 

Hair is lifeless and has no sensations. If we place a 
hand upon the head, we may feel the touch, but the 
feeling is not in the hair itself ; we feel the pushing of 
the hair against the nerves in the skin. We say that a 
cat's whiskers are very sensitive. The feeling is not in 
the hairs themselves, but in the very delicate nerves 

about the roots. 

* 

Hair grows on all parts of the body excepting the 
palms of the hands and the soles of the feet. In some 
places it hardly more than reaches the surface and is 
therefore so short that we do not notice it. Certain 
animals, like the cat and the dog, have very thick 
hair, which serves as a protection and covering for 
the skin. The hair of human beings is of no particular 



KIDNEYS AND SKIN AND THEIR DUTIES 161 



use except for ornament and for its protection to the 
head. 

The hair of the head has a tendency to fall out and 
produce baldness. This is especially true of the hair 
of men. Just why this is the case physicians do not 
know. Some think that it is due largely to the habit 
of wearing heavy hats with stiff rims which bind the 
scalp ; they advise the use of loose, cool hats. Others 
are of the opinion that " shampooing " the hair with 
the aid of diluted ammonia and soap, or other sub- 
stances, causes baldness. It is necessary, however, to 
keep the hair clean, and it may safely be washed with 
water containing a little soap. The soap should be 
carefully rinsed off and the hair thoroughly dried. 
Hair oil and hair restorers of all kinds should be 
avoided. 

Toe Nails and Finger Nails. — The toe nails and finger 
nails are parts of the epidermis developed in a special 
way. Figure 63 represents 
a cross section of a finger, 
showing the nail. The 
purpose of the nails is to 
protect the fingers and 
toes. They also help to 
beautify the hand, and 
they aid us in picking up 
small objects by enabling 
us to grasp them firmly. 

The nail grows outward from the root at the base, 
and unless the root is injured, the growth continues as 




Fig. 63. — A Section through 
the Tip or the Eixgee. 

Showing the nail. 



162 PHYSIOLOGY AND HYGIENE 

long as we live. The white " half moon " at the lower 
edge is where the nail is new and quite thin. If a nail 
is injured, it sometimes comes off. A new one will 
grow in its place, unless the root has been destroyed. 
We all dislike finger nails that are grimy or dirty at the 
ends. They should be kept clean and neatly trimmed 
with a knife or scissors. They should be cut only at 
the ends ; neither the surface of the nail nor the skin 
covering the root should be scraped or cut. 

Some young people form the habit of biting the 
nails. This is likely to injure the shape of the fingers, 
besides rendering the person disagreeable to all with 
whom he comes in contact. While various reminders 
may be employed to aid in overcoming the habit, such 
as some bitter substance placed upon the nails, the 
difficulty should be conquered by the exercise of will 
power. 

The Dermis. — The dermis, shown in Figure 61, is 
thicker than the epidermis, and is very different in 
structure. It consists principally of a mass of fibers, 
running in every direction. The fibers are packed 
close together on the side next to the epidermis, but 
they are less dense near the muscles, which lie below 
the skin. Tiny fat cells are found between the fibers, 
as shown in Figure 61. The dermis is full of blood 
vessels, so that, when cut, it always bleeds. It is also 
very sensitive, because of the many nerves it contains. 
Some of these nerves are particularly sensitive to heat 
and cold. 



KIDNEYS AND SKIN AND THEIR DUTIES 163 



FUNCTIONS OF THE SKIN 

As a Protection. — The epidermis is made of flat, 
scalelike cells, packed together so closely that they are 
a very great protection to the flesh beneath. Some 
of the cells may be seen in Figure 61. We can plunge 
the hand into poisons without injury, because the sub- 
stances cannot quickly make their way through these 
cells. Some diseases, as we shall see later, are caused 
by microscopic living germs getting into the body and 
growing there. The epidermis helps to protect us 
from such diseases by keeping out the germs. If they 
get through the skin, they may produce sores, boils, 
abscesses, or even more serious troubles. They cannot 
pass through the healthy epidermis, but often a slight 
scratch or bruise breaks the skin enough to let the 
germs in. As a result of the growth of these germs, 
the scratch becomes inflamed and painful, or perhaps 
develops a sore or boil. If the germs can be kept out, 
these sores will not appear. Special care should be 
taken to wash all cuts and bruises, and to cover them 
with a plaster or bandage so as to prevent bacteria from 
entering where the epidermis has been broken. 

As an Excreting Organ. — When we have been taking 
vigorous exercise, or on a very warm day, small drops 
of moisture, or sweat, appear on the forehead, the nose, 
and other parts of the body. This moisture is secreted 
by the sweat glands, of which we have about two and 
a half millions in our skin. 



164 



PHYSIOLOGY AND HYGIENE 



A sweat gland is too small to be seen with the naked 
eye, but it consists of a tube passing through the epi- 
dermis, and coiled up in a knot on the inside, as shown in 
Figure 61. This tube secretes the sweat, which passes 
out through a minute hole in the epidermis, called a 
pore, and is discharged upon the surface of the skin. 
The skin of the whole body is covered with these tiny 




Fig. 64. — A Bit of Skin as it appears under a Microscope. 
Showing furrows and pores. 

pores, each leading into a gland. Though they are 
found all over the body, there are more of them upon 
the forehead, the palms of the hands, and the soles of 
the feet than elsewhere. If we look at the skin of the 
fingers, we see that it is covered with irregular furrows. 
If we compare two fingers, we find that the furrows are 
unlike. The pores in the skin of the fingers are along 
the ridges between these furrows, as shown in Figure 
64 ; they may be seen with a magnifying glass. 



KIDNEYS AND SKIN AND THEIR DUTIES 165 

We notice the sweat only when it appears in drops 
upon the surface of the skin, or when it moistens the 
clothing. It is then being poured out of the glands in 
especially large quantities, but the glands are bringing 
it out all the time. The sweat is usually evaporated 
as fast as it comes to the surface, not becoming visible, 
but simply moistening the skin. If we hold the fingers 
close to a cold window pane, vapor collects on the glass. 
This shows that water is evaporating from the fingers, 
even though sweating is not apparent. 

The sweat itself is principally water, though small 
amounts of salt and other substances are dissolved in 
it. In fever, sweating is reduced very much or stops 
entirely. 

As a Regulator of Body Temperature. — The air, both 
in doors and out, is usually cooler than our skin. The 
air is constantly taking heat from the skin, cooling it 
and the blood which flows near the surface. The 
faster the blood flows through the skin, the faster it 
is thus cooled by the air. 

We have already seen that the skin is full of small 
blood vessels. These, like all the rest of the blood 
vessels, can be expanded and contracted as is needed. 
If the body is producing more heat than usual, brain 
centers cause the blood vessels in the skin to expand; 
the blood then flows faster, and more blood is cooled. 
If the body is not producing as much heat as usual, 
these blood vessels are made to contract. The blood 
is thus kept away from the surface and does not lose 
its heat by giving it out to the air. By opening and 



166 PHYSIOLOGY AND HYGIENE 

closing these blood vessels, the brain is able, without 
our knowledge, to increase or decrease the amount of 
heat lost through the skin. In this way our tempera- 
ture is controlled very closely and accurately. If the 
body is too warm, the blood vessels expand and let the 
heat out ; if too cold, they contract and keep it in. 

The nerves that are sensitive to heat and cold are 
located in the skin. When the warm blood pours 
through the skin, it warms these nerves and we feel the 
heat. When the blood vessels contract, so that the 
warm blood is kept away from the skin, these nerves 
are cooled by the air outside, and we feel cold. On a 
warm day we feel hot, not because the body is warmer 
than usual, but because the warm blood is flowing 
over the heat nerves in the skin. The body has practi- 
cally no sensations of heat and cold except those in the 
skin and in the lining of the mouth and the digestive 
canal. 

Cold-blooded Animals. • — Frogs, snakes, and certain 
other small creatures are called cold-blooded animals. 
The amount of heat produced in their bodies is not 
very great, and it passes off as fast as it is formed. 
The cold-blooded animals are never much warmer than 
the air about them. On a warm day they may be very 
warm, on a cold day they will be cold. Such animals 
are usually rather sluggish, especially in cold weather. 

Warm-blooded Animals. — The amount of heat pro- 
duced in our own bodies, and in those of such animals 
as dogs, cats, and horses, is comparatively large. This 
heat warms the blood to a certain temperature, which 



KIDNEYS AND SKIN AND THEIR DUTIES 167 

does not change with the temperature of the air, but 
remains about the same all through life. We call ani- 
mals whose bodies keep the same temperature warm- 
blooded. Their blood is usually warmer than the air, 
although on a hot summer's day the air may be the 
warmer. 

To keep the blood at this temperature requires con- 
siderable activity and a large amount of food, just as 
a considerable quantity of coal is required to keep our 
rooms very warm in winter. A cold-blooded turtle 
may live for six months without eating a mouthful; 
its activity is so slight that the small amount of food 
stored in the body is enough to sustain life, and no 
heat is needed to warm the body. A warm-blooded 
animal, on the other hand, must not only have a large 
supply of food, but it must have this food more or less 
regularly, and it can live but a short time if deprived 
of the regular supply. 

When we are in perfect physical condition, the tem- 
perature of our bodies is almost exactly 98J° F. If the 
temperature rises above this point or falls below, it is 
commonly an indication of ill health. We feel so much 
warmer on a hot summer afternoon than we do on a 
winter morning that it seems to us the temperature of 
our bodies cannot be the same, but a test with a ther- 
mometer would show, in both cases, just the 98^°, if we 
are well. 

Some warm-blooded animals — bears, for example — 
sleep throughout the winter. When thus asleep they 
burn less fuel (food) and do not keep warm ; their body 



168 PHYSIOLOGY AND HYGIENE 

temperature falls very much, but this does them no 
injury. When they wake in the spring, they begin to 
burn food more rapidly and are soon warmed again. 
Such animals are called hibernating animals. 

Regulation of Heat by the Lungs. — The skin is aided 
in regulating heat by the lungs. As our bodies are 
always producing much more heat than is needed to 
warm them, a large proportion of this heat must be given 
out, in order to keep the proper temperature. Much of 
the extra heat passes off in breathing. If we take in a 
breath of cool air and then breathe it out close to the 
back of the hand, we find that it is much warmer. 
The warm blood passing through the lungs has heated 
the air, and the blood is correspondingly cooled. The 
amount of heat which the body loses in breathing differs 
very greatly on different days. In winter the cold air 
may take much heat from the blood in the lungs. 

Sweating as a Means of regulating Heat. — In summer 
the air may be about as warm as the body, and in 
this case no heat at all would be lost through either 
the lungs or the skin by simply warming the air. In 
hot weather, therefore, another means of getting rid of 
the extra heat is provided. If we wet a finger and 
blow upon it gently, or hold it in the wind, the finger 
feels cool. The water is evaporated by the wind, 
and it takes a large amount of heat to evaporate water. 
The heat required to evaporate the water on the finger 
is taken from the finger itself, leaving this somewhat 
cooled. In the same way the sweat that is poured out 
upon the skin is evaporated, taking heat from the body 



KIDNEYS AND SKIN AND THEIR DUTIES 169 

and leaving this correspondingly cooler. The more we 
perspire the more the evaporation of the sweat cools our 
bodies. 

The sweat glands are connected with the brain 
through nerves, and when the body has too much heat 
a message from the brain makes the glands begin to 
secrete sweat profusely. The sweat is rapidly evapo- 
rated, and in this way we get rid of the extra heat that 
would make the blood too hot, if there were no way of 
escape. The evaporation of the sweat takes so much 
heat that the body is kept at its ordinary temperature, 
no matter how warm the day may be. 

Dogs do not sweat very much, and are apt to suffer 
greatly from the heat of summer. By their rapid 
breathing, or panting, they take in large quantities of 
air, which, passing through the lungs and taking heat 
from the blood, helps to keep down the temperature of 
the body. 

" Taking Cold." — There are people who seem to take 
a certain pride in their sensitiveness to drafts, and who 
are always ready, and expecting, to "take cold." Such 
persons usually do take cold oftener than other people, 
because they wrap their necks closely when out of 
doors, and in the house they sit near a register or with 
shawls about the shoulders if the air of the room is a 
bit chilly. 

Now " taking cold " is a habit which may be almost 
wholly avoided, if we will learn to treat the skin properly. 
In the first place, colds are not due to exposure to cold. 
Explorers do not take cold when in the Arctic regions, 



170 PHYSIOLOGY AND HYGIENE 

although they may do so after their return home. 
Soldiers can sleep on the damp ground or may be 
out in the rain for days at a time without catching 
cold. People who live out of doors seldom suffer from 
colds. We may feel cold from such exposure, but we 
do not take cold. We know from experience that we 
can have the face and the hands exposed when the tem- 
perature is very low, without catching cold. 

Yet it is true that we do sometimes suffer this 
disagreeable malady if cold air strikes some part of 
the skin which is usually protected. A slightly cool 
draft striking the bare shoulders may be sufficient 
cause. This fact has given rise to the idea that the 
best way to prevent taking cold is to protect the 
neck and shoulders by means of extra wraps. This 
is a wrong method. If we should cover our faces with 
wraps in the same way, they would soon become so ten- 
der that drafts striking them would produce colds. If, 
on the other hand, we should expose the neck as we do 
the face, it would soon become so accustomed to changes 
in temperature that it would be as impervious to cold 
as is the face. It is, then, very unwise to get into the 
habit of wearing furs or mufflers around the neck, or of 
turning up the coat collar about the ears. The extra 
protection may be necessary for comfort on an occa- 
sional extremely cold day, but the more we wrap the 
neck the more sensitive it becomes, and consequently 
the more liable we are to take cold. 



KIDNEYS AND SKIN AND THEIR DUTIES 171 



QUESTIONS 

1. What are the three waste products of muscle action ? 

2. What becomes of each of these waste products? 

3. What are excretions and secretions? Is sweat a secretion 
or an excretion? 

4. What organs produce secretions? 

5. Mention as many kinds of secretions as you can. 

6. What is the duty of the kidneys ? 

7. How are the kidneys constructed ? 

8. What are the two parts of the skin ? 

9. Where is the epidermis, and what are its characteristics? 

10. What are callosities and corns? Can callosities and blisters 
both be produced by rubbing? How? 

11. What are the parts of a hair ? 

12. How should we take care of the hair ? 

13. What are warts? 

14. How do the toe and finger nails grow? Have the nails any 
sensations ? 

15. What is the structure of the dermis ? 

16. How does the skin act as a protection ? 

17. What are the sweat glands? 

18. How is the heat lost through the skin? 

19. What are cold-blooded animals? 

20. If a cold-blooded and a warm-blooded animal were placed in 
an ice box, what effect would be produced on each ? 

21. How is the heat of the body regulated by the lungs ? 

22. Why do we need sweating to aid in regulating body heat ? 

23. How may we avoid taking cold? 



CHAPTER VIII 

THE CARE OF THE SKIN 

The skin, as we have learned, is an organ of great 
importance to the body. It is important as a protect- 
ing organ, as an organ of excretion removing waste 
products from the body, and it is at the same time the 
chief organ concerned in regulating the temperature. 

BATHING 

Cleanliness. — In order that the skin may keep in 
healthy condition, it is necessary that the sweat glands 
be kept free and open. The fat glands connected with 
the hairs constantly pour oil upon the skin, and the 
sweat glands secrete considerable solid material with 
the sweat. These substances remain upon the skin, 
and unless they are frequently removed they will in 
time clog the pores, and will also give to a person an 
unpleasant odor which renders him disagreeable to 
those about him. Frequent bathing and washing of 
the body is therefore desirable. No positive rule can 
be given as to the frequency with which we should 
bathe. A daily bath is advisable, although it is not 
essential to health. 

Cold Baths. — Cleanliness is not the only reason for 
bathing. The bath stimulates the skin, and this would 

172 



THE CARE OF THE SKIN 173 

render it of value even if it were not required for pur- 
poses of cleanliness. We have seen how the delicate 
blood vessels expand and contract with changes in tem- 
perature. The muscle fibers of these blood vessels and 
the nerves controlling them need exercise as much as 
do the other muscles of the body. Our habits of life 
give them little chance for this needed exercise; we 
keep our rooms uniformly warmed, and when we go 
out of doors on a cold day we cover all parts of the 
body except the face. Under these conditions the 
blood vessels in the skin are likely to become sluggish, 
and they need stimulation. The simplest way of giv- 
ing this is by means of the cold bath. 

Effects of a Cold Bath on the Skin. — A cold bath, 
whether a plunge in cold water, a shower bath, or merely 
a sponge bath, has always with a vigorous person the 
same effect. At first there is a sensation of cold, which 
causes the blood vessels to contract. For a short time 
the skin may be white and cold, but this is presently 
followed by what is called the reaction. The blood 
vessels open once more, allowing the warm blood from 
the interior to flow rapidly through the skin. The 
skin becomes flushed and warm, and there is a feeling 
of exhilaration, due to this after glow. 

A person should leave the water while still under 
the influence of the reaction. If he stays longer, he 
becomes chilly again, and will remain cold and uncom- 
fortable for hours. The length of time the after glow 
lasts depends upon the person, the temperature, and 
the water. It remains longer with salt water than 



174 PHYSIOLOGY AND HYGIENE 

with fresh. The greater the after glow, the more bene- 
ficial is the bath. If the body is rubbed vigorously 
with a rough towel after the bath, the glow is much 
increased, and the benefit correspondingly greater. 
Indeed, vigorous friction with a towel is of fully as 
much benefit as the bath itself. 

The expansion and contraction of the blood vessels 
thus brought about furnishes the skin with the needed 
exercise. If a person lives out of doors, exposed to all 
sorts of weather, such exercise is not necessary ; but to 
people spending most of the time in the house, such 
a bath is to the skin what the gymnasium is to the 
muscles. A warm bath does not accomplish the same 
purpose. It frequently makes one tired instead of 
exhilarated, and should therefore be taken only after 
the work of the day is done, instead of in the morning. 

Sometimes women and young girls who have not a 
great amount of vitality find that the cold plunge, or 
even the cold sponge bath, fails to give the desired 
reaction. In such a case the body should be accus- 
tomed to the cold water gradually. Little by little 
the space covered by the cold water may be extended 
until the skin has become sufficiently toughened so 
that the bath may be made general. This may usually 
be accomplished in the course of half a dozen mornings. 
To become accustomed to the cold plunge it is best to 
begin with slightly warm water, using it a little cooler 
each day, until we find we can endure water which is 
really cold. All young persons will find in the cold 
bath, either plunge or sponge, a source of pleasure 



THE CARE OF THE SKIN 175 

which, after they have become accustomed to it, the 
warm bath cannot give. 

Cold Baths a Protection against Colds. — This skin 
exercise renders the cold bath a protection against 
colds. If we will accustom ourselves to a cold sponge 
bath every morning, and will avoid covering the neck 
with thick wraps, we are much more likely to escape 
the habit of taking cold. The person who, by means of 
heavy wraps, protects his skin from exposure, and who 
takes only warm baths, is pretty sure to get into a con- 
dition that favors taking cold. He then regrets that 
he "takes cold so easily." The remedy may be in his 
own hands. It consists in adopting a mode of life that 
will give his skin the needed exercise. 

Hot Baths. — We can easily test the difference in 
effect of the cold and the hot bath. If we bare the 
arm and pour cold water upon it, then rub it briskly, 
the skin becomes red and warm with the after glow. 
If we plunge the arm into water as hot as can comfort- 
ably be borne it first grows red, then turns white, and 
there is no after glow. There are times, however, when 
a hot bath is beneficial. It may enable one who is rest- 
less and wakeful to go to sleep, since it draws the 
blood from the brain. When we feel a cold coming 
on, a hot bath or even soaking the feet in hot water 
may draw the blood from the throat and nose suffi- 
ciently to prevent the cold from developing. An occa- 
sional hot bath is also desirable for the cleansing of the 
body, even though cold baths are frequently taken. 



176 PHYSIOLOGY AND HYGIENE 

CLOTHING 

We should remember that we wear clothing for the 
purpose of comfort or adornment rather than to protect 
us from taking cold. For comfort it is necessary, in 
cold weather, to cover the body very completely with 
clothing. We should remember, however, that the 
clothing does not warm the body, but simply holds in 
our body heat, keeping it from passing off by way of 
the skin. Any clothing that conducts or sends off heat 
rapidly will cool the body quickly. Clothing that con- 
ducts heat slowly will keep the body warm. Linen and 
cotton carry the heat away rapidly, while woolen cloth- 
ing holds it back. We should therefore wear linen or 
cotton garments in the summer time, and woolen cloth- 
ing in the winter. Coarsely woven cloth, which is filled 
with air spaces, carries the heat away very slowly. 
Clothing made of such material is, then, the very best 
for keeping the body warm in cold weather. Similarly, 
two light garments, worn one over the other, are warmer 
than one heavy one of equal weight. The air space 
between the two acts as a "non-conductor" of heat. 

When we sleep, our bodies should be more warmly 
covered than when we are awake. A good rule to keep 
in mind is that for sleeping the feet should be warm 
and the head cool. As the body, during sleep, needs 
rest as much as possible, it ought not to be compelled to 
keep up any extra amount of heat. Paper is a material 
which readily holds back heat, and if a couple of news- 
papers be placed between two pieces of bed clothing 



THE CARE OF THE SKIN 177 

they do as good service in keeping the body warm as 
a blanket. 

BURNS 

Burns are very common injuries to the skin and are 
often very serious. In case of a slight burn we can 
usually relieve the pain for a time with cold water. 
One of the best applications for a burn is a paste which 
can be quickly made by rubbing soda or baking powder 
into some vaseline or sweet oil. Place this paste, which 
should be thin enough to spread easily, on a clean cloth 
and apply it so that it shall completely cover the burn. 
Another method is to apply a cloth wet in a solution of 
baking powder or saleratus and water. This solution 
is, however, less soothing than the paste, and the cloth 
must be soaked in it frequently. The burn should 
always be protected from the air. This may be done 
in an emergency by applying linseed oil, lime water, or 
even flour, to the place, but no cotton wadding should 
be put on the wound or anything else that might leave 
little particles on the surface. If the burn is neither 
very deep nor very extensive, it will heal readily; but 
if it is severe, it should be cared for by a physician. 

Life might sometimes be saved if people would re- 
member what to do in case the clothing catches fire. 
If the clothing gets afire, one should catch up any 
woolen article that may be at hand, wrap it closely 
around the burning clothing, and immediately lie down 
flat upon the floor or the ground, and roll over and over 
Without air the fire cannot burn, and the rapid rolling, 



178 PHYSIOLOGY AND HYGIENE 

even if one cannot reach any woolen stuff to serve as an 
extinguisher, will usually put out the fire. People 
have lost their lives by standing up while attempting 
to remove burning clothes. The flames rise, and if 
the person is standing, he is very liable to breathe the 
lire into his lungs. This causes almost instant death. 
If a person whose clothing is on fire loses his wits 
and starts to run, he should be thrown down as a means 
of saving his life, for running is very dangerous. He 
should then be wrapped in a rug, a blanket, a coat, or 
any similar heavy article that may be at hand, to 
smother the flames. After the fire is out, if the flesh 
of the person is burned, the clothing must be removed. 
Care must be taken, however, that the skin is not torn 
off. The clothing is likely to stick to the skin, and if 
it does so, it should be allowed to remain, at least where 
it adheres, the cloth being cut off around the place if 
necessary. If there are blisters, they should be opened 
and the liquid pressed out. Any further treatment 
should be given by a physician. 

FROSTBITES 

The freezing of fingers, toes, nose, or ears is not an 
uncommon occurrence on an extremely cold day. In 
such a case, the water in the blood and the muscles is 
actually turned to ice. If the frozen parts are thawed 
out slowly, no permanent injury may result ; but if 
they are thawed rapidly, serious trouble may follow, 
which may render amputation of the toes or fingers 
necessary. For this reason frostbites should be thawed 



THE CARE OF THE SKIN 179 

slowly. Rubbing the frozen parts with snow or cold 
water is recommended. This will thaw them out with 
the least possible danger of injury. In general, to 
preserve a part of the body that has been frozen, it 
must be promptly but very gradually thawed. After 
this the person may be warmed and given some warm 
drink, such as hot water, milk, or coffee. 

Many people wrongly suppose that the uncomfort- 
able affection of the feet known as " chilblains " is the 
result of frostbite. They are really due to getting 
the feet very cold and then warming them too quickly, 
and do not appear in children with a vigorous circu- 
lation. Warming cold feet over a register or in a 
stove oven is very likely to cause the difficulty. The 
best way to protect the feet against chilblains is to wear 
warm stockings and thick shoes in cold weather, and 
give the feet plenty of exercise. 

QUESTIONS 

1. Why should the sweat glands be kept free and open? 

2. What is the use of sweat? 

3. What is the effect of the cold bath ? 

4. What are the advantages of the cold bath ? 

5. How do cold baths act as a protection against colds ? 

6. What is the difference in effect between the cold and the 
hot bath ? 

7. What clothing is most suitable for summer? For winter? 

8. Are silk underclothing and stockings as useful as woolen ? 
Why? 

9. Why should the body be warmly covered during sleep ? 

10. What should be done when a person's clothing catches fire? 

11. What should be done for frostbite? 



CHAPTER IX 
ALCOHOL AND OTHER NARCOTICS 

Many people have the habit of using certain sub- 
stances which interfere with the health of various parts 
of the body. These substances are chiefly alcohol and 
narcotics. 

Alcohol is sometimes incorrectly called a stimulant. 
A true stimulant is some agent that increases the 
activity of some organ. For example, hot water stimu- 
lates heart action ; chewing rubber stimulates the secre- 
tion of saliva. Sometimes the term is wrongly used to 
apply to the action of some poison like strychnine that 
makes the body very excitable but really decreases 
instead of increasing its efficiency. 

Narcotics have just the opposite effect. They soothe 
and dull the action of the body and have a tendency to 
put people to sleep. Although narcotics and stimu- 
lants are thus very different, they are sometimes con- 
fused, since the same drug may seem to possess both 
effects. Alcohol, for example, is a narcotic. But its 
first action is to dull the powers of self-restraint in the 
brain, and this causes the person to do and say things 
that give the false impression of extra strength. For 
this reason it has been wrongly called a stimulant. As 
its action increases, however, its dulling effect becomes 
more evident and is more lasting. Its true action is, 
therefore, that of a narcotic and not that of a stimulant. 
When a larger quantity is taken, the narcotic effect is 
unmistakable. 

180 



ALCOHOL AND OTHER NARCOTICS 181 

OPIUM 

Opium is one of the most dangerous of narcotics. 
Morphine and laudanum are two common forms of the 
drug. Paregoric and soothing sirup, both of which 
contain opium, are especially dangerous, and should 
not be given to children. Opium dulls the senses and 
finally puts a person to sleep. The reason why it 
is so dangerous is that it has a tendency to produce 
a terrible craving for opium. 

A person begins by taking a small amount, possibly 
prescribed for him by a physician as a remedy for 
toothache, headache, or neuralgia. The drug not only 
soothes the pain, but produces a pleasant, restful feel- 
ing. Whenever the person has a pain which he wishes 
to relieve, he uses the same remedy, or he even imagines 
the pain for the sake of taking the drug. Soon the 
small doses with which he began cease to produce the 
desired effect, and he takes larger amounts. Before 
he suspects the fact, he has become an " opium eater," 
and no longer even pretends to make the excuse that 
he takes the drug as a medicine. 

Opium destroys the ability to think clearly and ruins 
the moral nature. The opium eater frequently becomes 
a liar and a thief. His health is undermined. He no 
longer finds pleasure in work or in recreation, and after 
a while even the drug itself ceases to give him relief or 
satisfaction. The use of the drug so affects his will 
power that when he finds himself a slave to the habit 
he has not the strength of will to restrain the appetite. 



182 PHYSIOLOGY AND HYGIENE 

When once the terrible habit has obtained a hold upon 
a man, it is almost impossible for him to control it. 
The use of opium in any form, except under the direct 
advice of a physician, is consequently exceedingly 
dangerous. Many physicians are unwilling to pre- 
scribe it, knowing as they do how easily the habit is 
formed. 

The use of chloral and cocaine is equally dangerous, 
the effects being similar to those of opium. 

TOBACCO 

Tobacco is a milder narcotic than opium, and one 
much more widely used. Tobacco contains a poison 
which is deadly when taken in considerable quantity. 
Whether or not the amount of this poison taken into 
the body by a grown person who smokes but little is 
enough to produce injury, there is no question about 
the ill effects of tobacco on young people, however 
moderately it may be used. Used freely, it is un- 
doubtedly injurious to adults. 

Moreover, mild narcotics like tobacco share with the 
stronger narcotics, though in less degree, that power of 
making the user want more and more of them. There 
are many other excellent reasons for refraining from 
the habit of using tobacco. 

1. Tobacco is of absolutely no value to the healthy 
body. It neither acts as a food nor does it serve any 
other useful purpose. 

2. The use of tobacco by young people may check the 



ALCOHOL AND OTHER NARCOTICS 183 

proper growth and development of the body. Careful 
study of college students has shown that those who are 
addicted to the use of tobacco are, on the average, con- 
siderably less developed than those who let it alone. 
The tobacco habit handicaps a boy in his physical 
development at the very start of life. 

3. The use of tobacco temporarily reduces one's 
muscular power, and may do so permanently. 

4. Its use often causes heart trouble. The " cigarette 
heart " is well known to physicians. Brain difficult}^ 
insanity, and even death are sometimes traceable to 
tobacco. 

5. It is an expensive habit. The money spent for 
tobacco could certainly be put to better use, and could 
be employed in ways that, to a young person at least, 
would give more pleasure and profit. 

6. It is a habit that renders one disagreeable to 
others and tends to selfishness. Most people who do 
not use tobacco, women especially, find the use of it 
by their acquaintances very disagreeable. Its use 
sometimes tends to selfishness and to a disregard of 
the feelings of others. 

7. The use of tobacco is likely to lead boys into inju- 
rious company, inviting them to idleness and to other 
bad habits. 

Of all forms of tobacco, cigarettes probably do the 
greatest amount of injury. A person who uses cig- 
arettes is likely to " inhale " the smoke. This means 
breathing the smoke into the lungs, which is far more 
injurious than simply taking it into the mouth. Boys 



184 PHYSIOLOGY AND HYGIENE 

in particular should know this, for cigarettes are gener- 
ally used by them on account of their cheapness. 

For these reasons the wise course is to leave tobacco 
alone. 

ALCOHOL 

One of the greatest dangers that a young person 
has to meet is that of acquiring the alcohol habit. 
Fortunately, it is not so common as the tobacco habit. 
Nevertheless, it has destroyed the lives of hundreds of 
thousands of young people, and has been a stumbling 
block in the way of hundreds of thousands of others. 
It has led to countless crimes, and has caused an ines- 
timable amount of poverty and suffering. The use of 
alcohol is particularly dangerous, because it frequently 
obtains a mastery over young people without their real- 
izing the fact. 

Use of Alcohol in Large Quantities. — The effect of 
alcohol upon the body depends largely upon the amount 
used. When speaking of the use of alcohol in large 
quantities, people mean its use in quantities sufficient to 
produce intoxication, or with a frequency that keeps the 
person more or less under its influence. The use of 
alcohol in such quantities is disastrous to health. It in- 
jures the action of the heart, interferes with circulation, 
and impairs the digestive powers. Moreover, it has a 
very important influence upon the moral nature. The 
drunkard loses his sense of responsibility and ceases 
to be a normal man. His whole body becomes dis- 
eased and unable to carry on its proper functions. His 



ALCOHOL AND OTHER NARCOTICS 185 

mind becomes dull and his ambitions disappear. The 
use of alcohol in large quantities destroys a man's 
chance of the highest success. Alcohol causes the 
death of thousands of men and women every year. 

Use of Alcohol in Smaller Quantities. — When alco- 
holic drinks are used in quantities insufficient to pro- 
duce intoxication, their effect upon the body may also 
be serious, although unfortunately not always apparent. 
The injury is so gradual that there may be little to call 
attention to it. Some people use wines or beers in 
small amounts for years without realizing that they are 
injured by them; nevertheless, alcoholic drinks, when 
habitually used, even in small quantities, frequently 
produce decidedly injurious effects. There is always 
the danger of forming the craving for more. 

The effect of using alcohol in small quantities does 
not appear at once. Its action when so used was 
shown recently by a series of experiments upon dogs, 
made by Dr. Hodge, of Clark University. Four 
dogs were selected from the same litter, all as nearly 
alike as possible. Two of them were given only ordi- 
nary food. The other two were treated in exactly the 
same way, except that they were given a small amount 
of alcohol with each meal. They were never given 
alcohol enough to make them intoxicated, and, taking 
into consideration the relative size of the dogs and 
a man, the amount given was relatively about as 
much as would be taken by many moderate drinkers. 
At first the four dogs were practically alike, but little 
by little differences began to appear between those that 



186 PHYSIOLOGY AND HYGIENE 

were given the alcohol and those that had nothing but 
the regular food. 

In the course of a few months the "alcohol" dogs were 
quite inferior in appearance to the other two. By the 
end of a year and a half the difference was very marked. 
The "alcohol" dogs were sleepy, and had a general ap- 
pearance of worthlessness. They were less active than 
the other dogs, and were much more quickly tired out. 
They would not bring back a ball when it was thrown 
for them so often as the others, and they frequently 
lay down to rest. In other words, the use of alcohol 
had lowered the intelligence, the brightness, and the 
muscular power of the dogs. 

If a moderate use of alcohol affects dogs so much 
in eighteen months, we may be sure that it has some 
injurious effect on the people who continue its use in 
this way for years. Whatever success in life has been 
made by a man who is a moderate drinker, he would 
certainly have amounted to as much without the alco- 
hol, and perhaps a great deal more. 

Competition is so great in these days, in business, in 
the professions, and, in fact, along every possible line of 
work, that the boy or young man of the present day 
needs to have every possible power of mind and body 
at his command. The man with clear and unimpaired 
brain, with a healthy, well-cared-for body, with body 
and brain controlled by a determined, resolute will — 
he is the man who will make a success in the coming 
years of the twentieth century. 

The Alcohol Appetite. — We have already learned that 



ALCOHOL AND OTHER NARCOTICS 187 

one of the most dangerous things about alcohol is its 
tendency to create a desire for more. This desire may 
be very slight at first, but it is likely to grow. More- 
over, although at first a small amount of alcohol is all 
that a person wants, or can drink, when his body be- 
comes accustomed to this amount, he almost without 
knowing it takes a little more. Quite unconscious of 
how serious a thing it is, he slowly increases the amount 
used, sometimes by taking a larger amount of weak 
liquors and sometimes by taking stronger ones. He 
begins with beer and finally uses distilled liquors. The 
appetite grows with indulgence, and sooner or later 
it may become so firmly fixed that he is quite unable 
to break it. 

Danger of the Appetite. — The fact that the appetite 
grows slowly and imperceptibly is what makes alcohol 
so dangerous. If a boy or young man could appreciate 
how the appetite is increasing, if he could realize to 
what it is likely to lead him, and if he could under- 
stand at the beginning how he is slowly becoming bound 
by a habit, he would in most cases curb the habit before 
it developed much strength. But the habit grows im- 
perceptibly, and at the same time undermines his will, 
until it finally produces disastrous results. 

The continued use of alcohol, moreover, is likely to 
crush out all desire to reform. The alcohol appetite 
might be overcome in most cases if the person had a 
sufficiently strong desire to do so ; but his will power 
and his desire for a better life are taken away as the 
appetite grows upon him. 



188 PHYSIOLOGY AND HYGIENE 

It is undoubtedly true that thousands of people who 
begin to use alcohol in small quantities, develop the 
alcohol appetite and are finally mastered by it. Every 
boy who begins to drink runs the danger of developing 
such an appetite. He may not become mastered by it, 
but experience has shown that in many cases the boy 
finds himself in time mastered by the habit. It is never 
possible to predict what will be the result. Drunkards 
are commonly made out of boys and girls who do not 
intend to use enough alcohol to injure them. If a boy 
never begins to use alcoholic liquors, he will never be- 
come a drunkard ; but if he does begin, even in a mild 
way, he places himself among those from whom drunk- 
ards are made. The only sure way to avoid this danger 
is to avoid its beginning, and, in avoiding that, the boy 
also insures for himself a healthier body, a clearer brain, 
and a better chance for success in life. 

QUESTIONS 

1. What is the difference between a stimulant and a narcotic ? 

2. What is the effect of opium, and why is it a dangerous 
drug ? 

3. Why should tobacco not be used? 

4. What is the effect upon the body of using alcohol in large 
quantities ? 

5. What are the effects of a moderate use of alcohol ? 

6. What do you regard as the strongest reason for avoiding 
alcoholic drinks? 



CHAPTER X 
THE NERVOUS SYSTEM 

Every large factory must have a superintendent. 
Otherwise the persons employed to do various tasks 
would work independently of one another, and as a 
result little would be accomplished. The superin- 
tendent is indeed the most important man in the 
entire factory. 

Within our bodies various actions are going on. 
About five hundred muscles, numerous glands, and many 
other organs are constantly at work. If they should 
act independently there would be great confusion. In 
our bodies, however, as in the factory, there is a super- 
intendent, whose duty it is to control all the different 
parts and keep them working in harmony with each 
other. A few of the body actions, like the beating of 
the heart, can take' place without direct command from 
the superintendent, but with the others the order of 
the superintendent is required before the organs will 
work at all. 

The muscles will never act unless they are com- 
manded to do so by the central controlling organ. As 
we have already learned, the organ that corresponds 
in the body to the superintendent of a factory, and 
that controls the numerous activities, is the brain. 

189 



190 PHYSIOLOGY AND HYGIENE 

The brain is connected with every part of the body- 
by a series of nerves. This is the organ with which 
we think, and by means of which we will to do any- 
thing. The brain also causes a great many actions to 
take place in our bodies without any knowledge on 
our part. We do not realize, for instance, that mes- 
sages are being sent from the brain to the blood vessels 
of the skin, causing them to open or shut. 

THE BRAIN 

The brain fills the bony box called the skull. Figure 
65 shows its shape and structure. It is a very large 




(Breathing 
>//<7 }Va so Motor 
ta)Heart Control 

'Swallowing 

Fig. 65. — The Human Brain. 

organ, that of an adult weighing some three pounds. 
There is considerable difference in the weight of vari- 
ous brains. The more intelligent races commonly have 
large brains, while those of less intelligence usually 



THE NERVOUS SYSTEM 191 

have smaller ones. There are, however, among individ- 
uals, some remarkable exceptions to this general rule. 
The brain is a very complicated orgam As shown in 
Figure 65, it is divided into three main parts, each of 
which has special duties to perform. 

The Medulla Oblongata. — Forming the very lowest 
part of the brain is the medulla, or medulla oblongata, 
which lies between the spinal cord and the main part 
of the brain. It is not more than one and a quarter 
inches in length, yet it contains the centers that control 
some most important body actions. As Figure 65 indi- 
cates, the breathing, the vasomotor system (i.e. expan- 
sion and contraction of blood vessels), the heart control, 
and swallowing, together with other functions, are the 
special care of this part of the brain. 

The Cerebellum. — A little higher than the medulla 
is situated a larger rounded part of the brain, about 
half as large as a baseball, called the cerebellum. It 
is somewhat flattened and, as Figure 65 indicates, is 
marked with numerous furrows. It lies over the 
medulla. The cerebellum is thought to influence mus- 
cular action. We have seen how wonderfully the 
muscles are adjusted so as to act together, as, for 
instance, when a boy throws a stone. This is sup- 
posed to be accomplished in part through the action 
of the cerebellum. 

The Cerebrum. — The cerebrum is the largest part of 
the brain. Figure 65 shows that it is covered with 
deep furrows which divide it into folds called convo- 
lutions. These folds are not exactly alike in all brains, 



192 



PHYSIOLOGY AND HYGIENE 



though the larger ones are almost always present. The 
cerebrum is divided by a very deep furrow into two 

parts, called the right and the 
left hemispheres. The division 
is indicated in Figure 66. The 
two parts are connected with 
the body in such a way that the 
right hemisphere controls the 
left side of the body, and the 
left hemisphere the right side 
of the body. The cerebrum 
is the part of the brain that 
is active in thought and in the 
exercise of will power. What 
we call the " mind " is centered 
in the cerebrum. It is the 
center which starts and con- 
trols the activity of the body. 




Fig. 66. — The Nervous 

System. 

Showing the brain and the 

spinal cord with its nerves. 



THE SPINAL CORD 

A long, soft, white cord, 



called the spinal cord, starts 
from the lower end of the medulla (shown in Fig. 66}, 
and passes down through the backbone or spine. The 
vertebrae of the backbone protect the cord on all sides. 
In other words, the spinal cord runs inside the back- 
bone (see Fig. 43, p. 126). As may be seen from Fig- 
ure 66, the cord is not of the same thickness throughout 
its length, but it becomes gradually smaller as it passes 
down the back. At the lower end it divides into fine 



THE NERVOUS SYSTEM 



193 




ngtion 



Fig. 67.- 



threads. When in its proper position inside the back- 
bone, the cord is covered not simply with bones, but 
with certain softer membranes, which act as a further 
protection, so that it is very thoroughly guarded from 
injury. 

If we cut the cord directly across, it will appear as 
we see it in Figure 67. Like the brain, it is divided by 
deep furrows into 
two parts, the 
right half and the 
left half. The fur- 
rows, as the figure 
shows, do not ex- 
tend all the way 
across the cord, 
but the two halves 
are united at their 
center. At the 

very center of the cord, Figure 67 shows a rather irreg- 
ular mass, shaped somewhat like the letter H, with four 
arms running off to the sides. This material is of a 
dull gray color, and is called the gray matter. It con- 
tains nerve cells, which start and receive nervous im- 
pulses, or "messages." Outside the gray matter is 
a substance, whiter and more glistening, called the 
white matter of the cord. This consists of nerve 
fibers, whose duty it is to carry up and down the cord 
the nervous impulses which are started and received by 
the gray matter. 



Anterior Root 



Two Pieces of the Spinal 
Cord. 



Showing the gray matter and the two roots 
of the spinal nerves. The arrows show 
the direction of the stimuli. 



194 PHYSIOLOGY AND HYGIENE 

THE NERVES 

The brain may be regarded as the superintendent of 
the body. If this superintendent is to have any control 
over the different organs in the body, it must in some 
way be connected with them. The superintendent of 
a factory often has telephone connection with every 
room in the building by means of electric wires which 
run in various directions. In a similar way the super- 
intendent of our body, the brain, is connected with 
every part of the body by a series of connecting fibers 
which we call nerves. 

Figure 66 shows these nerves coming from the spinal 
cord as it passes down through the back. The nerves 
start in the gray matter of the cord, and then pass from 
the cord between the vertebrae, extending outward into 
the body to connect with all the organs controlled by the 
brain. As may be seen from Figure 67, each of these 
nerves rises from the cord in two branches, known as 
roots. The front branch, called the anterior root, carries 
nervous impulses from the brain to the muscles; while 
the other, the posterior root, carries nervous impulses 
from the skin and other organs to the spinal cord and 
thence to the brain. 

After the two branches unite, as shown in the figure, 
they form what we call a nerve trunk. Such a trunk 
is made up of thousands of nerve fibers, or wires, bound 
together in a bundle. Each fiber runs to a distinct 
part of the body. Figure 68 shows a bundle of fibers 
that make up a nerve. A nerve trunk usually con- 



THE NERVOUS SYSTEM 



195 



tains some fibers that carry impulses toward the brain 
and some that carry them away from it. A few 
nerves, however, contain only one kind of fiber. By 
means of these hundreds of thousands of nerve fibers 
every muscle, every gland, every 
part of the skin, receives and 
sends nervous impulses to and 
from the brain. 

The wire that rings an electric 
bell is always connected with two 
different pieces of apparatus, with- 
out which it would be useless. At 
one end of the wire is placed the 
bell to be rung ; at the other end 
there is a battery, which starts the 
electric current that rings the bell. 
The wire serves simply to connect fylinder— 
the battery with the bell. The 
nerves in our body serve, in a 
similar way, to connect two pieces 
of apparatus placed at their ends, 
corresponding to the battery and 
the bell. 

If we could examine carefully 
the nerve fibers, we should find 

that many of them end in a minute, somewhat rounded 
body, with numerous branches extending from it on 
all sides (Fig. 69). This body is called a nerve 
cell and it corresponds in its work to the battery 
that starts the electric impulse to ring the bell. Since 



Medullary 
JheathA 

Axis I Alerve 



Single. 
Nerve 
Fiber 
Fig. 68. — A Nerve. 
Showing on the right a 
nerve composed of 
the many nerve fibers 
and on the left a single 
nerve fiber. 



196 



PHYSIOLOGY AND HYGIENE 



the nerve cells are the organs that start and receive 
nervous impulses, we should expect to find them most 
numerous where stimuli are sent out to the various 
organs ; and this is the case. There are a great many 

nerve cells in the spinal cord, 
and in the brain they are so 
numerous that we cannot 
even conceive of their num- 
ber. It is estimated that 
the brain contains 9,000,000,- 
000 such cells. 

We may think of one of 
these cells as a tiny battery 
which can start nervous im- 
pulses over the nerve fibers 
leading from it, or as a bit of 
apparatus which receives im- 
pulses coming over other 
nerves. Each nerve cell is 
connected by a long nerve 
fiber with some part of the 
body. There is no part of 
the body, no matter how 
small, that is not connected 
with the nerve cells of the brain and spinal cord. 

The nerve cells in the brain are, most of them, near 
the surface. The rest of the brain consists of a com- 
plex tangle of fibers running in all directions, somewhat 
like the series of wires that run into a central telephone 
station ; only instead of a few hundred such wires the 
brain has hundreds of thousands. 




Fig. 69. — A Nerve Cell. 

Showing branches and a single 

nerve fiber arising from it 



THE NERVOUS SYSTEM 197 



QUESTIONS 

1. What is the relation of the nervous system to the rest of 
the body? 

2. What is the brain? 

3. What are the parts of the brain ? 

4. Where is the medulla? What is its work? 

5. If the cord is cut across below the medulla, why would 
breathing stop at once? 

6. What is the cerebellum ? What actions does it control? 

7. How is the cerebrum arranged? What powers does it 
control ? 

8. What is the spinal cord? Where is it situated? 

9. What does a cross section of the spinal cord show of its 
structure ? 

10. What is the purpose of the nerves? 

11. If the posterior root of a nerve (see Fig. 67) were cut, could 
the person receive sensations through that nerve ? Why ? 

12. How do the brain and spinal cord resemble an electric 
battery? 

13. Why are there more nerve cells in the brain than elsewhere ? 



CHAPTER XI 
THE NERVOUS SYSTEM IN ACTION 

DUTIES OF THE NERVES 

If we touch the hand with a hot match, instantly we 
have a feeling of pain and the hand is drawn away. 
The hand is connected with the brain by the nerve 
shown in Figure 70. If this nerve of the arm should 
be cut at the point indicated in the figure, and then the 
match should be touched to the hand, no pain would 
be felt. What is more, if we should wish to move the 
hand, we should be quite unable to do so. Cutting the 
nerve, therefore, destroys all sensation and all power 
of motion in the hand. The cutting does not injure 
the muscles. They would still be able to contract, if 
they were stimulated by an electric shock. Moreover, 
cutting does not destroy sensation; for if the end of 
the nerve which is still attached to the brain (called 
the central end in Fig. 70) were pinched, we should 
feel pain. And what seems most strange of all, we 
should think that we felt the pain in the hand and 
fingers, although the nerve had really been touched at 
a point above the elbow. These facts teach us several 
things in regard to the action of the nerves. 

1. The nerves form a line of communication be- 
tween the brain and spinal cord and the muscles. 
Muscles are caused to act by means of nerves. 

198 



THE NERVOUS SYSTEM IX ACTION 



199 



2. Muscles commonly act only when they receive a 
nervous impulse from the brain or spinal cord. 

3. Nerves form a means of communication between 
the different parts of the body and the brain, by which 
messages (sensations of pain, for example) are sent to 
the brain. 

4. Sensations are really felt 
in the brain, although we seem 
to feel them in other parts of 
the body. 

The burning match touched 
to the skin of the hand causes a 
message to travel up the nerve, 
but no feeling of pain results 
unless the message reaches the 
brain. When, therefore, the 
nerve is cut or compressed so 
that the message cannot get to 
the brain, no sensa- 
tion of pain is felt. 
If the message does 
reach the brain, 
however, it produces 
pain, and we locate 
this pain in the hand 
where the match touched it. The brain always locates 
the pain at the end of the nerve which brings the 
message, and for this reason it sometimes makes ' a 
mistake. 

For example, the nerve from the hand has all our 




Fig. 70. 

Showing the connection of the hand with 
the brain by a nerve. It is supposed 
to be cut above the elbow. 



200 PHYSIOLOGY AND HYGIENE 

lives brought messages to the brain from the hand. 
Now if this nerve is cut above the elbow, as in Figure 70, 
it can no longer bring messages from the hand. But 
if the central end, also shown in the figure, is pinched, 
the nerve carries the impulse to the brain. Since the 
brain has always received over this nerve impulses 
coming from the hand, it is now not able to recognize 
that this impulse does not come from the same place. 
So the sensation seems to come from the hand, when in 
reality it started from above the elbow. 

These facts make it clear that the nerves are merely 
conducting wires carrying impulses that start at their 
ends. Some impulses start at the outer ends and 
go to the brain, producing sensation there. Other 
impulses start in the brain and pass down the spinal 
cord and out to the muscle fibers, where they cause 
motion of the muscles. Messages travel thus through 
the nerves in both directions, and by means of them 
the brain is placed in communication with every part 
of the body. 

The nerve fibers by means of which sensation is 
communicated to the brain are called sensory nerve 
fibers. Those which convey the impulses from the brain 
to the muscles are called motor nerve fibers. 

DUTIES OF THE SPINAL CORD AND MEDULLA 

The spinal cord has more complicated duties to per- 
form than have the nerves. Carrying messages to and 
from the brain is simply one of these manifold duties. 
As can be seen from Figure 66, large numbers of nerves 



THE NERVOUS SYSTEM IN ACTION 201 

enter the spinal cord, and in the cord itself they pass 
up to the brain. These nerves are all so arranged that 
messages passing through them from the right side of 
the brain reach the left side of the body, and messages 
starting from the right side of the body reach the left 
side of the brain. 

Independent Action of the Cord. — We have learned 
that the spinal cord contains nerve cells as well as nerve 
fibers. If these nerve cells serve the same purpose as 
batteries, we should naturally expect that the spinal 
cord could do something besides simply carry messages. 
The cord does indeed have another kind of duty, called 
reflex action. If, for example, a finger is pinched, an 
impulse is started which passes to the spinal cord on 
its way to the brain. In the spinal cord it excites 
certain cells. These in turn excite other cells, from 
which instantly motor impulses are sent out from the 
spinal cord to the muscles controlling the arm and 
hand, causing contraction and the withdrawal of the 
finger. This is called reflex action, and it takes place 
very quickly — in less than one tenth of a second. 
The original sensory impulse, of course, may pass on 
to the brain, where it will cause pain, but the instan- 
taneous withdrawal of the finger from danger was a re- 
flex action, and might take place without brain action. 
Reflex action does not require any will power and can 
take place just as well when a person or an animal is 
asleep as when he is awake. In the case of some ani- 
mals it will take place when the brain has been entirely 
removed from the body. 



202 PHYSIOLOGY AND HYGIENE 

A reflex action never starts itself. It must always 
be started by some outside stimulus. To produce such 
a reflex action something must stimulate the body in 
such a way as to cause a message to go to the spinal 
cord. The action never begins in the spinal cord itself, 
but always at the outer ends of the nerves, usually 
because something touches the skin or some other part 
of the body. 

Although the brain is not necessary to reflex action, 
still it is possible for the brain partly to control such 
action, especially if the action is a repeated one, or one 
of which we are aware in advance. For example, if 
the bottom of the foot is tickled, the foot is pulled 
away. This is a reflex action and will take place when 
we are asleep just as readily as when we are awake. 
If, however, we are awake and know what is to be 
done, we can often use sufficient will power to prevent 
the foot from being pulled away even when it is 
tickled. The will power is exerted through the brain 
alone and, therefore, in this case the brain stops the 
reflex action. But under some circumstances, even 
when we are awake, our will power is not strong 
enough to prevent the reflex action. If a bit of food 
becomes caught in the windpipe, for instance, it will 
cause us to cough, and no matter how hard we try, we 
shall be unable to keep from coughing until the food is 
dislodged. The coughing is a reflex action and, in this 
case, is too strong to be controlled by will power. 

Reflex Action in the Medulla. — A study of the me- 
dulla, indicated in Figure 65 as at the top of the spinal 



THE NERVOUS SYSTEM IN ACTION 203 

cord, shows that this part of the brain controls a 
number of the most important vital functions. Here 
are centered the powers that control breathing, the 
rapidity of the heart beat, swalloiving, the size of the 
blood vessels (thus regulating circulation), and some 
others of less importance. These actions are all reflex. 
It will be recognized that these actions are the primary 
functions of life. If they continue, the person will 
live, even though all others cease for a time. The 
activity of the cerebellum and cerebrum may stop for a 
while and yet the person may continue to live if the 
medulla is not injured; but if the medulla is injured, 
it may stop the heart beat and breathing at once, and 
thus produce instantaneous death, even though the rest 
of the brain is uninjured. The medulla may thus be 
said to be the center of the vital functions. The cen- 
ters controlling these vital functions may act quite 
independently of will power or consciousness, as they 
do when we are asleep. 

THE CEREBELLUM AND CEREBRUM 

The Work of the Cerebellum. — The cerebellum also 
controls reflex actions more complex than those connected 
with the spinal cord. Such actions as walking are 
at first controlled by our will power and are not reflex 
at all. After a time, however, they become reflex in a 
measure, and take care of themselves. When we first 
begin learning to play the piano we must think care- 
fully of the action of each finger, but after playing for 
a number of years, we no longer need to attend par- 



204 PHYSIOLOGY AND HYGIENE 

ticularly to the fingers. We simply place our hands 
on the piano and the fingers fall naturally upon the 
proper keys and make the proper motions for pro- 
ducing music. A skilled pianist can talk to a friend 
and at the same time continue playing, paying no atten- 
tion to his fingers and yet never striking wrong notes. 
Through long practice certain parts of his brain, prob- 
ably in the cerebellum, have learned to take care of the 
motions of the fingers, so that the mind is free to 
attend to something else. Some of these complex 
actions are controlled by the cerebellum, but physiolo- 
gists as yet know little about them or where they are 
located. 

The Work of the Cerebrum. — The upper and larger 
part of the brain, the cerebrum, is the real center from 
which all the impulses of our conscious activity come. 
It is the center that regulates the conscious action of 
the whole body. 

The relation of the cerebrum to the other parts of 
the body may be best understood by the comparison 
already used, of the superintendent and the factory. 
The cerebrum itself is like the general superintendent 
who directs the work of the whole factory. The vari- 
ous centers in the cerebellum and the spinal cord are 
like the foremen of different rooms or of different parts 
of the work. When the superintendent wishes some- 
thing to be done, he sends a message to the foreman of 
a special room, and the foreman gives the order to the 
individual workmen. In this way the superintendent 
is not obliged to pay attention to the detailed work of 



THE NERVOUS SYSTEM IN ACTION 205 

every employee, but can give his time to planning the 
operations of the factory as a whole. 

So the mind, when it wishes some special action to 
be performed, such as moving the hand, sends a message 
to some of the centers in the lower parts of the brain, 
and these forward the necessary commands by way of 
the nerves to the muscles in the arm and hand, so that 
the hand is moved. After the various centers have 
learned their duty, the mind itself does not need to 
attend to the little details. Our minds are then free 
for thought. We can talk as we play on the piano 
because the mind has trained some of its servants 
in the cerebellum to look after the contractions which 
cause the fingers to touch the keys correctly. If these 
servants in the cerebellum are not carefully trained, the 
plans made by the mind will not be properly carried 
out. Our education, from the time of our earliest 
childhood, is largely given to training the servants of 
the mind. We sometimes call the training of these 
servants acquiring habits. 

THE IMPORTANCE OF HABITS 

We can readily see how necessary it is that we should 
have well-trained servants to do our work, and, there- 
fore, that we should form good habits. After we have 
once formed a habit it is very difficult to get rid of it. 
The training of children at home and at school is for 
the purpose of developing right habits of thinking and 
acting, in order that, after they become men and 



206 



PHYSIOLOGY AND HYGIENE 



women, they may be properly guided by these good 
habits. 

By doing the same thing again and again the body 
becomes so accustomed to a certain kind of action that 




Pig. 71. — The Brain in Position. 
Showing the location of the different powers in the brain. 



it will be "second nature" to perform that action. 
Every time that we do something in a certain way it 
becomes easier to do the same thing in that way again. 
If the habit is an injurious one, like the alcohol habit, 



THE NERVOUS SYSTEM IN ACTION 207 

we come more and more under its influence by yielding 
to it. If, on the other hand, the habit is a useful one, 
we fit ourselves better for life every time we perform 
the action. This is as true of moral actions as it is of 
muscular movements. If we exaggerate the facts when 
we tell a story, we are forming a habit that will grow 
until we become liars, unless the fault is overcome. If 
we dawdle over our books instead of giving our best 
thought to study, we are forming habits of inattention 
that are likely to hinder successful work through life. 
We are constantly forming habits whether we wish to 
do so or not. Inasmuch as these habits are to be our 
servants through life, it is wise to see to it that we form 
those that will be useful rather than those that may do 
us harm. 

We know very little in regard to the location of the 
different powers of the cerebrum. Figure 71 indicates 
about all that is really understood. The power of think- 
ing is probably connected with the front of the brain, 
certain powers of motion with the middle, while some 
of the senses are located in the back part of the brain. 

THE CARE OF THE MIND 

Our entire lives are directed by the mind. We 
should, then, take the best possible care of these minds 
of ours. A few facts of importance are worth remem- 
bering. 

Sleep. — We cannot continue one form of activity 
very long without some kind of rest, for both the body 
and the mind need to rest. The most complete kind 



208 PHYSIOLOGY AND HYGIENE 

of rest for mind and body is sleep. When we sleep* 
the mind is largely free from its usual forms of activ- 
ity, although our dreams show us that the mind is not 
entirely inactive. The deeper the sleep the less distinct 
will be the dreams. The amount of sleep needed by 
various people differs greatly. A young child needs 
twelve hours out of the twenty-four for sleep, a growing 
boy or girl about ten, while most grown people require 
only about seven or eight. Some persons seem to get 
on very comfortably with even less. It is best to 
remember, however, that we are much more likely to 
have too little sleep than too much. 

Sometimes a boy or girl takes a kind of pride in 
sitting up late and studying far into the night. This 
is likely to be done just before examination time, 
under the impression that better preparation can thus 
be made for the tests. This is a great mistake. Sit- 
ting up late to study, the night before, usually renders 
one less fitted to pass an examination. The many facts 
we try to cram into our heads during such midnight 
study are not all found there the next morning. We 
are weary, and the brain does not work as it should. 
To get a good night's rest is a much better method of 
preparing for an examination than to study until the 
mind gets tired. 

Concentration. — The person who accomplishes the 
most is the one who is able to turn his whole attention 
to his work. When we are thinking of several things 
at once, we can give none of them careful considera- 
tion. If, when we are supposed to be studying, we let 



THE NERVOUS SYSTEM IX ACTION 209 

our thoughts wander to the athletic field, then to the 
woods and the trout brook, then to something going on 
in the schoolroom, bringing them back finally with an 
effort to the lesson, it will take us much longer to master 
the lesson than it will if we give our attention to that 
and nothing else. The pupil who applies his mind 
wholly to the lesson he is preparing will do his work 
much more quickly and much better than his neighbor 
across the aisle who studies one minute and dreams the 
next. The ability to think of one thing at a time is 
largely a habit, and one of the most useful of habits. 
It is one that can and should be acquired by every boy 
and girl. If we allow our thoughts to wander from 
one thing to another, we shall let this habit master us, 
and in later life we may, as a result, find it very diffi- 
cult to think continuously and vigorously. 

Recreation. — The mind needs recreation as well as 
work and rest. It ought to be employed at times in 
such a way as to obtain relief from its required tasks. 
We ought just as much to give our minds recreation as 
to give them sleep. Without it we become dull, and 
our bodily health is likely to suffer. Recreation is 
even more necessary for the boy or girl who wishes to 
be a scholar than it is for the person who works prin- 
cipally with his muscles. 

Each of us should choose his own recreation. It 
should be something that gives pleasure and enjoyment, 
and it must be something that we do from choice, not 
because we must. It is also necessary that the kind 
of recreation a person takes should occasionally be 



210 PHYSIOLOGY AND HYGIENE 

changed. Much of a person's success as well as happi- 
ness in life depends upon his having enjoyment. We 
can work harder and do better, if we may look forward 
to pleasant recreation as the reward for faithful labor. 

Dependence of the Mind upon the Body. — Our minds 
and our bodies are related so closely that their welfare 
cannot be separated. If we allow our bodies to become 
weak from lack of exercise or want of the proper kinds 
of food, our minds will not be vigorous. The most 
active mind, and the one that thinks best, will be found 
in a healthy body. The boy or girl who enjoys books 
and study is the one who must be especially careful to 
give proper attention to health. The student must 
have recreation, exercise, good, wholesome food, fresh 
air and sunshine, if he wishes to preserve at its best 
that valuable treasure, his mind. The boy or girl who 
neglects mind for body cannot compete in after life with 
the person who studies hard. On the other hand, the 
boy or girl who neglects bodily health for the sake of 
knowledge is sure to fall behind the one who develops 
a healthy mind in a healthy body. 

The Mind and Narcotics. — One matter of importance 
in connection with the proper care of the mind is keep- 
ing it free from the control of all narcotics. The use of 
alcohol has its first and most important effect upon the 
action of the brain. The first result of taking alcohol 
seems to be to excite the brain, and thus alcohol has been 
wrongly called a stimulant. This excitation is really 
one of the results of its narcotic action. Its action upon 
the brain is really the opposite of a stimulant, for almost 



THE NERVOUS SYSTEM IN ACTION 211 

at once it begins to dull the mental powers. Tliis dulling 
action becomes very noticeable when large amounts of 
alcohol are used. 

Careful testing has shown that one who has taken 
even small quantities of alcohol cannot add a column 
of figures so quickly as usual, or that if he can add 
the column as quickly he may fail to do it accurately. 
He may be able to talk more rapidly, but he will com- 
monly not think so clearly. He acts more slowly than 
usual. If he is hunting, he loses his straight aim ; if 
setting type, he works less rapidly and makes more 
mistakes. He is perhaps not conscious of all this, and 
feeling somewhat excited and exhilarated, he may 
actually think that he is doing more work than usual, 
while he is really doing less. He may believe himself 
to be bright and witty, when he is uttering only foolish 
jests. The man with whom he has business dealings, 
and who keeps sober, gets the better of him in a bargain. 
The more alcohol he uses, the greater its dulling action 
on the brain. Finally he may notice it himself, but 
even though he does not appreciate it, others find that 
he is not able to talk intelligently ; he becomes confused 
and stupid, and finally is unable even to walk straight. 
When he is completely under the influence of alcohol, 
nearly all the actions of his body cease, except breathing 
and the beating of the heart. 

There are various degrees in this dulling effect of 
alcohol. It is slight when small amounts are used, and 
complete when large quantities are taken. How large 
an amount a person can take without having his judg- 



212 PHYSIOLOGY AND HYGIENE 

ment seriously affected it is impossible to say. But 
even the very small amounts appear to have some 
dulling action upon the mind. Some of the keenest 
thinkers have found that their power of concentrated 
thought is dulled by taking even very small amounts of 
alcohol. The primary effect of alcohol is to disorganize 
the nervous system. Its effect may be slight if only 
small amounts are used, but the effect is nevertheless 
there, the same in kind though less in degree even when 
small amounts are taken. 

QUESTIONS 

1. How do we know that sensations are felt only in the brain ? 

2. If the spinal cord were cut across at the shoulders, what 
effect would it have on the lower parts of the body ? 

3. What have the nerves to do with sensation? 

4. What is reflex action ? 

5. Where is reflex action controlled ? 

6. If a person's foot is tickled, what action and reflex actior 
occur? Do you suppose the foot would be pulled away if the 
person were asleep ? 

7. What reflex actions are controlled by the medulla ? 

8. What kind of reflex actions are controlled by the cerebellum? 

9. Why should you think coughing to be a reflex action? 

10. What are the duties of the cerebrum ? 

11. Why is it important that good habits be formed ? 

12. In what ways can the mind be cared for ? 

13. Why is sleep necessary ? 

14. If a person goes to sleep while sitting up, he is likely to fall 
over. Why is this? Would he be as liable to fall over as he 
would be if he fainted ? 

15. Why should we learn the habit of concentration? How 
may it be learned? 

16. What is recreation ? Why is it necessary? 

17. What is the effect of alcohol upon the mind? 



CHAPTER XII 
THE SENSES 

The brain is shut up tight in its bony box, the skull. 
It has no direct contact with the external world, and 
yet it succeeds in finding out very well what is going 
on outside of our bodies, just as a telegraph operator, 
shut up in his little office, can learn what is going on 
in the world. As we have learned, the brain is con- 
nected with the outer parts of the body by the sensory 
nerves, which bring messages, or impulses, from the 
exterior. They extend from every part of the body to 
the spinal cord and the brain, and bring messages from 
every part. The messages, when they reach the brain, 
produce what are called sensations, and it is through 
the sensations that we get our knowledge of the outer 
world. 

There are several outside forces that may excite the 
sensory nerves to send impulses to the brain. One of 
the most common of these is a touch upon the skin, 
which sends an impulse that gives rise in the brain to 
a sensation which we call touch. Similar sensations 
can come from every part of the skin. There are also 
several forces capable of starting impulses through spe- 
cial nerves. Light, for example, starts impulses from 
the eye through its nerve., sound from the ear. Through 

213 



214 



PHYSIOLOGY AND HYGIENE 



these special nerves we get our sense of sight and of 
hearing. Some substances excite impulses from the 
tongue, giving a sense of taste, and others from the 
nose, giving the sense of smell. These act by means 
of special organs, situated at the ends of particular 
nerves, which we call sense organs. These represent 
four of the so-called special senses. 

THE SENSE OF SIGHT 

The Eyeball. — The eye itself is shaped like a ball, as 
shown in Figure 73, although as we look at it in a person's 
. . face it appears quite 

unlike a sphere. This 
is because we see only 
a small portion of the 
front of the eye, the 
rest being hidden be- 
hind the eyelids. The 
only part of the eye- 
ball that we can see is 
just what appears be- 
tween the eyelids, and 
the eye will look 
large or small accord- 
ing to whether the eyelids are wide open or partly 
closed. Different people appear to have eyes of vari- 
ous sizes, but the dimensions are really always about 
the same ; that is, the diameter is close to one inch. 

The eyeballs are set in deep sockets in the front 
of the skull, as may be seen from Figure 73, only the 




Eig. 72. — The Eye, viewed from in 

Front. 
Showing the tear gland and tear duct. 



THE SEXSES 215 

front surfaces being exposed. The sockets protect the 
balls from injuries which might come from blows. 

The Eyelids. — Two folds of skin hang over the eye, 
one above and the other below, as may be seen in Figure 
73. These are eyelids, which open and close over the 
eye. When closed, they serve to protect the eye and 
also to keep its surface clean and moist. Even when we 
are awake the eyelids close every few seconds. We are 
quite unconscious of this movement of the eyelids, but 
we can easily observe it by watching the eyes of some 
one near us. The front of the eye is extremely delicate, 
and if the lids did not constantly cleanse its surface, 
and if the tear secretions did not wash the dust away, 
the eye would become inflamed, and the sight be affected. 
The eyelids, by means of their long lashes and their 
exceedingly quick motion, serve also to guard the eye 
against accident. The hairs on the edges of the lids, 
called the eyelashes, assist in keeping out the dust. 

The Tear Gland. — The lids are aided in keeping the 
eyes clear by the tears. A small lachrymal gland, or 
tear gland, is lodged just above each eye, on the side 
away from the nose. This gland produces a watery 
liquid, which flows down over the eye and keeps its 
surface moist. The liquid flows over the eyeball to 
the inner edge of the eye near the nose, where there is 
a tube, the tear duct, leading to the cavity inside the 
nose, as shown in Figure 72. The tears, after washing 
the surface of the eye, pass through the duct into the 
nose and the throat, and are then swallowed. Usu- 
ally the gland produces just liquid enough to wash the 



216 



PHYSIOLOGY AND HYGIENE 



eyeballs and to pass easily down the lachrymal duct. 
But when a person cries, the tears are produced so 




Nerve 



Fig. 73. — The Eye, viewed from the Side. 
Showing its shape, the socket, and the attachment of muscles. 



rapidly that they cannot all pass through the duct into 
the nose. They then overflow and run down the cheeks. 

The Eye Muscles. — Six small muscles are attached to 
each eyeball to move it. One is on the top, one on the 
bottom, one on each side, and two others have an oblique 
position. Figure 73 shows the form and position of 
these muscles. By the contraction of the muscles the 
eyeball can be turned in any desired direction. 

Structure of the Eyeball. — If we examine a photog- 
rapher's camera, we find that it has three chief parts. 
There is (1) a dark chamber, the box of the camera, 
closed so as to admit light only from the front. In the 
opening in front which admits the light there is (2) a 
lens, which makes an image of the object to be photo- 



THE SENSES 



217 



graphed ; at the back of the camera is (3) the sensitive 
plate, upon which the picture is taken. 

The human eye is made upon much the same plan 
as the camera, although differing in details. Like the 
camera, it has a dark 
chamber and a lens, and 
also a sensitive surface 
at the back. If we ex- 
amine Figure 74, we can 
see how closely the eye 
and the camera may be 
compared. The eyeball 
is a dark chamber, which, 
like the camera, admits 
light only from the 
front. At the point 
where the light is ad- 
mitted there is a lens, 
shown in Figure 74, and 
at the back of the eyeball is a sensitive surface called 
the retina, shown in Figure 75. Between the front of 
the eye and the retina the eyeball is filled with trans- 
parent liquids, through which the light can easily pass. 

Light enters the eye from the front, passing through 
the small opening known as the pupil (Fig. 75). 
Just inside of this pupil is a transparent lens. The 
lens is so shaped that the rays of light are changed in 
their direction and come together at the back part of 
the eye. When they come together they produce a 
little picture or image of the objects from which the 




Fig. 74. — A Comparison of the 
Structure of the Camera and 
the Eye. 



218 PHYSIOLOGY AND HYGIENE 

light comes. This image is similar to what we see on 
the ground-glass screen at the back of a photographer's 




Fig. 75. — A Diagram representing a Section through 
the Human Eye. 



camera, which shows a picture of the objects toward 
which the camera is pointed. In the same way a little 
picture is formed upon the back part of the eye. The 
part of the eye upon which the image is formed is the 
retina, and is the sensitive part. 

The retina is full of nerves, and in some wonderful 
way, not fully understood, these nerves send impulses 
to the brain, by which the brain receives and recognizes 
the picture. If the nerves that connect the eye with the 
brain were cut, the message could never reach the brain, 
even though the image should be formed on the retina. 
If the eye were injured so that the image could not be 
formed on the retina, we could not see, even though the 
nerve were in good condition. 



THE SENSES 219 

The lens that forms the picture on the retina is not 
able to form a picture of both a near and a distant 
object at the same time ; hence we cannot see clearly- 
near objects and distant objects at the same moment. If 
we are observing a hill some distance off, and wish to 
look at a pencil in our hands, the shape of the lens 
changes a little so that the pencil becomes sharply 
pictured on the retina, but, at the same time, the hill 
necessarily becomes blurred to our sight. 

Nearsightedness. — If the eyeball is of exactly the 
right shape, ordinary objects will be sharply pictured 
upon the retina. If, however, the ball is a little too 
long, distant objects will not be clear, not sharply- 
focused as we say, but they will look blurred. A per- 
son with such eyes cannot see distant objects clearly, 
though he can readily see objects quite close to the 
eyes. We say he is nearsighted, and, in order to see 
clearly, he is obliged to wear glasses especially prepared 
to overcome his difficulty. 

Nearsightedness is very common. It is often due to 
improper habits of study. We are likely to lean over 
a desk or a table when we read, thus bringing the book 
very close to the eyes. This habit, if continued, is 
certain to cause such changes that the eyes, which at 
first could see clearly, become little by little so affected 
that only near objects can be clearly seen. Such near- 
sightedness is quite common among people who spend 
their early years in study. The difficulty is less com- 
mon among those who live out of doors and who do 
little or no reading. If we will take pains to sit erect 



220 PHYSIOLOGY AND HYGIENE 

when reading or studying, and to hold our books no 
nearer than a foot or eighteen inches from the eyes. 
If this is not a comfortable distance, the eyes need the 
attention of an oculist. If we hold a book within 
six inches of the eyes, we shall be quite sure to 
develop nearsightedness. 

Color Blindness. — Some people have the sense of 
color poorly developed, and we call them color blind. 
This does not mean that they cannot see any color at 
all, but that they confuse the various colors. The 
most common form of color blindness is the inability 
to distinguish clearly reds from greens. Since red and 
green are the colors used as signals on railroads and 
steamboats, a pilot or a railroad engineer who cannot 
distinguish them readily may commit such blunders 
that accidents will result. Persons who are to hold 
responsible positions on railroads or steamboats are 
accordingly required to have their eyes specially tested 
for color, and no one who is color blind should ever 
think of taking such a position. The difficulty is more 
common among men than among women, and no remedy 
for it is known. 

Care of the Eyes. — 1. T^he eyes were made to be 
used, and it does them no harm to exercise them con- 
stantly. If, however, they are used on work that 
requires close attention, such as reading or sewing, 
they become tired and should frequently be allowed a 
moment for rest, such as is gained by closing the eye- 
lids or by looking at distant objects. 

2. We should not abuse the eyes by reading in a 



THE SENSES 221 

dim or flickering light. Nor should a bright light, like 
the sun's rays, be allowed to fall upon the page we are 
reading. We should never look directly at a bright 
light. Daylight is better than artificial light. 

3. The only proper position for holding the head 
when we read is erect. Reading, when lying on the 
back or in a hammock, is very injurious to the eyes. 
We must not forget, moreover, that using the eyes 
means also working the brain. When the brain is 
tired, one is often inclined to lie down and read a book 
— setting the tired brain to work again, and under 
conditions bad for the eyes themselves. 

4. If a child has difficulty in seeing or his eyes are 
inflamed, he should be examined by an oculist. Head- 
aches are frequently due to trouble with the eyes, and if a 
child has a tendency to headache, his eyes should be 
examined. It frequently happens that the trouble 
with the head may be cured by the use of glasses pre- 
scribed by a competent oculist. 

5. Particles of dust that get into the eyes are 
usually carried off with the tears by way of the 
tear duct, and a few winks remove them. If this is 
not sufficient, the trouble may frequently be remedied 
by lifting the upper eyelid with the fingers and drawing 
it down over the lower eyelid. If this does not remove 
the particle of dust, it may be taken out by some com- 
petent person who can pass gently over the eyeball the 
end of a soft handkerchief rolled up to a point. If this 
attempt fails, a physician should be called. The eyes, 
in such cases, should never be rubbed. The eyes are 



222 



PHYSIOLOGY AND HYGIENE 



organs too delicate and too important to be treated by 
incompetent persons. If one has trouble of any kind 
with his eyes, he should consult a physician or an 
oculist. 

THE SENSE OF HEARING 

The Ears. — The two projections on the sides of the 
head, which we commonly call the ears, have very lit- 




Afe/re 



Eustachian 
Tube,, tot he 
throat 

Fig. 76. — The Ear. 

A section through the " stony bone," showing the parts of the ear. 

tie to do with hearing. They are only bits of carti- 
lage covered with skin, which serve, perhaps, to col- 
lect waves of air, and probably make sounds a little 
louder. The real hearing organ is the inner, or true 
ear, which is wholly inside the head and embedded in 
the bones. The ear itself is in the middle of the 
hardest bone in the body, called the stony bone. The 



THE SENSES 223 

ear is thus more thoroughly protected from external 
injury than any other organ. 

The ear is a very complicated organ. Its general 
structure may be seen from Figure 76, which shows a sec- 
tion through the side of the head, giving the chief parts 
of the ear. The passage from the outside to the true 
ear, as the figure shows, is slightly bent. In it there is 
secreted a little wax, which helps keep it moist and flexi- 
ble. The passage is closed at the inner edge by a mem- 
brane which is stretched across. This is the tympanic 
membrane. Is is tough and elastic. Earache in chil- 
dren is usually caused by sores in the ear ; these occa- 
sionally make little holes through the membrane, which 
interfere somewhat with hearing. Sometimes very loud 
noises, like explosions, break the membrane and make 
the person deaf. 

Figure 76 shows that beyond the membrane there 
is a cavity. It is known as the ear drum, or tympanic 
cavity, and is also sometimes called the middle ear. 
The ear drum is filled with air, w T hich enters it through 
a tube in the lower side. This tube leads to the 
throat, as indicated in Figure 76, and is opened every 
time we swallow. In this way the drum is filled with 
air, and the pressure of the air in the drum is kept the 
same as the pressure of the air outside. If this tube 
becomes closed, as sometimes happens with inflamma- 
tion of throat or nose, the air within the ear is partly 
absorbed, so that the pressure inside becomes less and 
the membrane is pushed in by the pressure of the out- 
side air. This affects the hearing injuriously. This 



224 PHYSIOLOGY AND HYGIENE 

is the reason why throat troubles are very apt to extend 
to the ears and interfere with hearing. Indeed, the 
most common cause of deafness is to be found in diffi- 
culties of the throat. Catarrh in the throat is one of 
the first things that a physician attends to in most cases 
of difficulty in hearing. 

In Figure 76 it will be seen that three small bones 
(malleus, incus, and stapes) are stretched across the 
cavity of the middle ear. The outer of these ear bones 
is attached to the membrane and the inner one con- 
nects with the inner ear, which contains the real hearing 
organ. In this inner ear are many nerves. Sound is 
produced by waves of air which enter the ear and shake 
the tympanic membrane. This shakes the bones at- 
tached to it, and by their motion the effect of the air 
wave is transferred to the inner ear, where it reaches 
the nerves. This shaking or vibration upon the nerves 
starts nervous impulses which travel rapidly to the 
brain. When the messages reach the brain they pro- 
duce a sensation which we call hearing. 

Hearing. — Our ears tell us very little in regard to 
sounds except their loudness or softness, &}±d their 
pitch (high or low). Our power of determining dis- 
tance is limited. If we know what causes a certain 
sound, we can determine something of its distance by 
the loudness. We judge the distance simply by the 
loudness of the sound as compared with what we should 
hear if the sound were nearer or farther away. If, for 
example, we hear the whistle of a locomotive, and it 
sounds faint, we are sure that the engine must be a long 



THE SENSES 225 

distance away, because we know that the sound itself is 
really very loud. If, on the other hand, we hear the 
buzz of a mosquito, and it sounds loud, we know that 
the insect is close to the ear. We can determine the 
distance of sound in no other way than by the compara- 
tive loudness. 

Our power of determining the direction from which 
sound comes is not much greater. Noises coming to 
the ear from the side of the head may sound louder in 
one ear than they do in the other, and in that case we 
judge that the sound is on the side of the head where it 
seems loudest. Sometimes we unconsciously turn the 
head around a little, until we find that the sound appears 
to be loudest when the head is in a certain position. 
We then conclude that the noise comes from the direc- 
tion toward which the ear is turned. But this test is 
by no means accurate. 

Care of the Ears. — The ears require very little care. 
The use of solid objects, like pins or needles, to remove 
the ear wax is very unsafe. The ears may be kept suffi- 
ciently clear of wax by means of the little finger, which 
should be pushed downward as it is placed in the open- 
ing. Very loud sounds close to the head are likely to 
do harm. Boxing children's ears is liable to injure the 
membranes within. Pain in the ear may sometimes be 
relieved by placing hot cloths upon the ear ; but if it 
persists, a physician should be called. It is well to re- 
member that deafness is most commonly produced by 
throat troubles, and if one has any difficulty in hearing, 
he should first of all look to the condition of his throat. 



226 PHYSIOLOGY AND HYGIENE 

Slight deafness is not unusual with children ; it renders 
a pupil apparently inattentive and dull. The child does 
not realize that he has any difficulty in hearing, and 
very likely neither his teacher nor his parents suspect it. 
Therefore a child who is inattentive should have his 
hearing tested. If deafness is the cause of the difficulty, 
a physician should be consulted at once to remedy the 
defect, if possible. 

THE SENSE OF TASTE 

By the sense of taste we learn something of the nature 
of liquids. Solid substances do not produce taste. It 
is true that many solid bodies have a certain taste, when 
taken into the mouth, but not until they are more or 
less dissolved in the saliva. If we rub the tongue dry, 
and then place upon it a lump of sugar, we notice no 
taste at first, but, as soon as the liquids of the mouth 
begin to dissolve the sugar, we perceive the sweet taste. 

Location. — The sense of taste is located in the mouth, 
but not, as is commonly supposed, wholly in the tongue. 
The upper side of the tongue has a sense of taste, but 
the under side has not. Besides this, the roof of the 
mouth, especially at the back, has a sense of taste. When 
a substance is rolled around by the tongue at the back 
of the mouth, we find there the strongest sense of taste. 

The Tongue. — The tongue of a healthy person is of a 
pinkish red color. If it is otherwise, the stomach is 
probably out of order. One of the simplest methods 
employed by physicians for detecting signs of certain 
diseases is an examination of the tongue. When this is 



THE SENSES 



227 



covered with a whitish or yellowish coating, or when it 
is bright red, the physician knows that something is 
wrong. 

If we examine the tongue carefully, we find that it 
appears much as in Figure 77. It is covered with 
numerous little bunches 

or papillae, which differ Papillae withtostt buds Tons]f 

in appearance and vary 
in use. Some of them, 
particularly those at the 
back of the mouth, are 
associated with the sense 
of taste and are called 
taste buds (see Fig. 77). 
The tongue itself is 
made up principally of 
muscles, which run in 
many directions and 
enable us to move the 
tongue very easily. In 
addition to the muscles 

there are glands which secrete a watery material that 
keeps the tongue moist. There are also many blood 
vessels and nerves, among them some which are 
particularly connected with taste, and which carry to 
the brain the messages that enable us to determine the 
presence of sweet, sour, or bitter substances in the 
mouth. 

Tastes. — We think of the substances that we eat 
as having many different tastes. All kinds of tastes 




Fig. 77. — The Tongue. 
Showing the papillae on its surface. 



228 PHYSIOLOGY AND HYGIENE 

may, however, be classified under four heads, — bitter, 
sweet, acid (sour), and salt. These different tastes are 
not perceived equally well in all parts of the mouth. 
We taste sweet things most delicately at the tip of 
the tongue, and bitter things at the back part of the 
mouth. We are very apt to confuse tastes and smells, 
and many sensations that we call tastes are really 
tastes and smells combined. When we drink a glass of 
soda water, for example, we have the sweet taste of the 
sirup, but the gases from the soda water pass into the 
nose and produce a very strong sense of smell. The 
two together are what we call the pleasant taste of 
the soda water. Many other so-called tastes are largely 
smells, as can be tested by blindfolding a person, hold- 
ing his nose so that he cannot catch the odor, and then 
giving him successively small pieces of apple, onion, 
and potato. 

Duration of the Sense of Taste. — Our sense of light 
is gone at almost the instant the light ceases to shine 
into the eye, and the sense of sound stops as soon as the 
vibration that produces it ceases or becomes too distant 
to affect the ear. The sense of taste, however, does 
not cease so quickly, but it may last many seconds, or 
even several minutes, after the substance tasted has 
been swallowed, partly because some of the substance 
remains in the mouth. An unusually bitter taste, like 
that of quinine, may last as long as half an hour. 

The sense of taste easily becomes tired, and in this 
respect it is quite different from the sense of sight. We 
may use our eyes all day long, and yet see as clearly at 



THE SENSES 229 

night as in the morning. But, if we continue to use our 
sense of taste for even a few minutes, it loses its acute- 
ness. We can test this characteristic by eating a lemon. 
Food does not have so pleasant a taste at the close of a 
meal as at its beginning, so we often finish our dinner 
with a highly flavored dessert to please our taste, which 
has by this time become dull. 

Our sense of taste is one of our greatest enjoyments, 
but to obtain the most pleasure from it we must not 
gratify it too much. If we live upon plain food, with 
an occasional luxury, we shall find more enjoyment in 
it than do people who are constantly eating highly 
flavored foods. The luxury gives special pleasure only 
when it is unusual. If we should eat the most delicious 
food constantly, it would soon come to give us less 
enjoyment. The bulk of our food should be such as 
satisfies the appetite rather than the taste. Finely 
flavored substances, like candies, sauces, and sweets in 
general, should be used in comparatively small quanti- 
ties, if we wish to enjoy them as much as possible. 

THE SENSE OF SMELL 

The sense of smell enables us to determine the pres- 
ence of certain gases. Only substances that are in the 
form of a gas or vapor can be smelled. Rose water is a 
liquid, but the only part that we smell is the vapor that 
rises from it. The amount of vapor required to excite 
the sense of smell is exceedingly minute. If a bottle of 
peppermint oil be opened for a few moments, it will give 
off a vapor that will fill the room and will be smelled 



230 



PHYSIOLOGY AND HYGIENE 



Olfactory 
Nerves 



by every one present. Yet if the bottle of liquid be 
weighed in the most delicate scales, there will be no 
perceptible difference in the weight before and after the 
bottle was opened. No other sense is as delicate as that 
of smell. 

Location. — The sense of smell is located in the cavities 
of the nose. The two nostrils lead into two large cavi- 
ties above the mouth, 
separated from each 
other by a bony parti- 
tion. The cavities 
extend backward to 
the throat. They are 
partly filled with large, 
thin, folded bones, 
which bend around so 
as to form curved sur- 
faces. They give a 
large amount of ex- 
posure to the air, as it 
passes over them. 
Upon these bones are the nerves of smell (olfactory 
nerves), as shown in Figure 78. Vapors entering the 
nose, as we breathe, act upon these nerves in such a 
way that they send messages to the brain, and produce 
in the brain the sensation that we call odor or smell. 

Its Use. — The sense of smell in human beings is not 
so well developed as in some animals, or so useful. We 
may occasionally notice by its aid the presence of inju- 
rious gases, such as illuminating gas which is escaping 




Fig. 78. — A Vertical Section of the 

Nose. 

Showing the nerves of smell. 



THE SENSES 231 

from a burner. Sometimes, also, we perceive through 
the sense of smell the presence of some body or substance 
which gives off a special odor, but which is concealed 
from our eyes. With some animals the sense of smell 
is much more keen than it is with human beings. A 
dog can follow his master's footsteps by means of his 
very keen sense of smell. 

The acuteness of the sense of smell is blunted by con- 
tinued use even more than is that of taste, as we can 
readily prove with cologne or other strong odor. The 
first whiff of cologne on a handkerchief gives a strong 
sensation. If, however, we bury our face in the hand- 
kerchief and continue to breathe the odor, we cease to 
smell the cologne. It order to perceive it again, we 
must remove the handkerchief from the nose and let 
the smelling organs rest for a time. 

OTHER SENSATIONS 

We frequently say we have five senses, — seeing, hear- 
ing, tasting, smelling, and feeling. The first four of these 
are quite distinct. The fifth, which we call feeling, is 
made up of several different kinds of sensations. There 
are really two different senses in the skin, — touch 
and temperature. In addition to these the term feeling 
usually covers the pain sense, hunger, thirst, and some 
other sensations. 

The Touch or Pressure Sense. — The skin is sensitive 
to the touch or pressure of objects. Whenever a sub- 
stance presses even very lightly upon the skin it excites 
the nerves in such a way that nervous impulses are 



232 PHYSIOLOGY AND HYGIENE 

sent to the brain, which builds out of these impulses an 
impression, more or less distinct, of the object that 
touched us. We can easily test this by shutting our 
eyes and letting some one touch us with different kinds 
of unknown objects. The whole skin is thus an organ 
of touch, although it is more sensitive in some places 
than in others. 

Through the messages that come to the brain from 
the skin we not only get a sensation that the skin is 
touched, and that the object touching it causes a cer- 
tain amount of pressure, but we know quite accurately 
what part of the body is in contact with the object. 
We can tell whether the ring is on the finger or is lying 
on the palm of the hand, and whether it is on the little 
finger or the thumb. The delicacy with which we can 
determine where the skin is touched differs very much 
on different parts of the body, as can be easily discov- 
ered by experiment. It is most delicate at the tips of 
the fingers and the tip of the tongue. We can tell 
within a twenty-fifth of an inch where an object, like a 
needle point, touches the skin of the finger tips or the 
tongue. The sense of location is much less delicate on 
the back of the fingers, and still less so on various parts 
of the arms and shoulders. Upon the back of the shoul- 
ders it is least delicate of all ; in fact, we cannot deter- 
mine within two and a half inches where an object 
touches the back part of the shoulder. We can see 
from this that the parts of the body most used are the 
ones in which the sense of touch is the most delicate. 

It is the sense of touch, or of location of touch 



THE SENSES 23B 

sensations, that gives us our most intimate knowledge 
of the nature of objects outside our bodies. By the 
sense of touch alone we can tell whether such objects 
are rough or smooth, whether they are blunt or sharp, 
whether they are solid or liquid. 

The Temperature Sense. — When a warm body touches 
the skin, nervous impulses go to the brain, and we have 
a feeling of warmth. The skin, in general, is sensitive 
to both cold and heat, though some points on the skin 
are sensitive to heat and not to cold, while others are 
sensitive to cold and not to heat. The warm and 
cold spots are very close together, so that a body no 
larger than the head of a pin will in some places touch 
both. Every part of the body has a certain tem- 
perature, and if some object warmed to that exact 
temperature touches the skin, the pressure of the object 
will be felt, but it will seem to be neither warm nor 
cold. If, however, the object is a little warmer than 
is the skin at the point where it touches, it will seem 
warm ; if it is a little cooler than the skin at that 
point, it will seem cold. The temperature of the 
skin is not just the same on all parts of the body. 
The temperature of the hand is usually a little lower 
than that of the forehead, so that an object which feels 
warm to the hand may feel cool to the forehead. The 
forehead itself feels warm to the hand. 

If we step in cold weather from a carpet to a bare 
floor, the floor feels colder to the feet than the carpet, 
although the two are actually of the same temperature. 
The bare floor draws the heat away from the feet more 



234 PHYSIOLOGY AND HYGIENE 

rapidly than the carpet does. Any object feels cool 
when it takes heat away from the body rapidly. If it 
withdraws no heat from the body, we feel that the 
object touches the skin, but we feel no sensation of cold 
resulting from the contact. Some substances draw heat 
more rapidly than others, and this is why, in cold 
weather, for example, metal objects seem colder than 
cloth to the touch. 

Sense of Pain. — Almost any nerve which carries mes- 
sages to the brain will carry a sense of pain, if it is 
strongly excited. If the pain is slight, we can deter- 
mine very closely where it comes from; but if it is 
severe, we cannot locate it so accurately. A slight 
toothache, for example, can be located in the proper 
tooth, but when it is severe, it seems to come from the 
entire jaw, or the whole side of the head. Occasionally 
the whole upper part of the body appears to be in pain, 
although the trouble is confined to a single tooth. 

We find it hard to realize that pain is of any use, but 
it really is of great value. If it did not hurt to burn 
the fingers, children would get their fingers so badly 
burned as to render them useless. In fact, they would 
probably destroy the fingers entirely before they were 
old enough to know how to take care of themselves. 
Pain thus warns us to guard our bodies from accidents 
and disease, and to keep them in as good a condition as 
possible. Pain is a warning to our bodies, and we should 
heed it as carefully as does the engineer the danger 
signal beside the railroad track. 



THE SENSES 235 

The Muscle Sense. — We seldom hear any one speak 
of the muscle sense, but it is really of considerable im- 
portance. It is the sense by which we know when and 
how much we contract our muscles. Even when we 
shut our eyes we can move our fingers very accurately, 
knowing almost exactly how much the muscles contract. 
Let us say, for example, that we will allow one hand to 
rest upon the table while we close our eyes. If, while 
our eyes are still closed, another person lifts the hand, 
we can tell very accurately by means of the muscle 
sense how far it has been lifted. This sense is of great 
importance, for it enables us to control our actions and 
to move our muscles together. If we could not feel 
how much we move the muscles, we could not possibly 
make the body motions that require the contraction of 
a number of muscles at the same time, as when we 
throw a stone. The muscle sense is not situated in 
any particular place, but is present in all parts of the 
body, especially in the joints. 

QUESTIONS 

1. How does the brain get a knowledge of the world? 

2. What are the chief sense organs ? 

3. What is the shape of the eyeball, and where is it located? 

4. What are the eyelids? What is their purpose? 

5. Where are the tear glands located? What is their use? 

6. How are the eyeballs moved ? 

7. What are the principal parts of the eye ? 

8. Why is it desirable to sit erect when reading? 

9. If the lens of the eye should become opaque, what would be 
the result? 



236 PHYSIOLOGY AND HYGIENE 

10. Some persons cannot distinguish between green and ripe 
cherries. Can you explain the reason? 

11. In what five ways should we care for the eyes? 

12. Where are the real hearing organs ? 

13. What are the important parts of the ear? 

14. How do the ears enable us to hear ? 

15. How should we care for the ears ? 

16. If two colors are mixed, do we get a new color? If two 
sounds are mixed, do we get a new sound or do we hear both 
sounds ? 

17. If you close the nose and swallow, what effect is produced 
in the ears? Can you explain why? 

18. Where is the sense of taste located? 

19. What is the structure of the tongue ? 

20. Mention several duties of the tongue? 

21. What may be said of the duration of the sense of taste ? 

22. Where is the sense of smell located ? How may this sense 
be dulled? 

23. How could you tell whether soda water, without sirup, has 
a taste or only a smell ? 

24. What three sensations compose the sense of feeling ? 

25. What is the use of the touch or pressure sense ? 

26. What do we learn from the sense of heat and cold ? 

27. Lay the palm of the hand upon the cheek. Does the hand 
appear warm or cool ? Do the same upon the forehead. What do 
you observe? 

28. Of what use is pain ? 

29. Of what importance is the muscle sense? 



CHAPTER XIII 
HEALTH AND DISEASE 

The body is a very delicate piece of machinery, as we 
can readily appreciate. It needs to be treated carefully, 
but most of us have bodies that will keep in good 
condition if we care for them properly. 

The Body cures Most of its Own Ills. — The human 
body is such a beautifully constructed machine that it 
will of itself take care of the ordinary slight illnesses. 
If we have a cold, the body soon cures it ; wounds are 
rapidly healed; broken bones are mended; digestive 
troubles usually disappear. All of these little maladies 
the body itself can care for. We need simply to do 
our part toward keeping in good condition by eating 
plain, wholesome food, taking plenty of exercise, and 
living as much as possible out of doors in the fresh air 
and sunshine. 

Many people have the idea that the proper way to 
treat ailments of all sorts is to take medicines. This is 
a great mistake. Medicines cannot cure disease. The 
most they can do is to aid the body to right itself. 
Most people would be better off by letting nature cure 
their little ailments, giving her the aid that comes from 
such simple remedies as baths, soaking the feet in hot 
water, and rubbing, rather than by dosing themselves 

237 



238 PHYSIOLOGY AND HYGIENE 

with drugs. Medicines should be used only under a 
physician's guidance. The constant use of drugs rather 
weakens than strengthens the general physical powers. 
If people used fewer drugs and more common sense, 
took less medicine and more exercise, wore fewer wraps 
in winter and spent more time out of doors, we should 
hear less about sickness, and the whole race would be 
more robust. 

Disease. — When the machinery of the body is out of 
order we speak of the condition as sickness or disease. 
The causes of diseases are numerous. Sometimes they 
are the result of improper food habits, or intemperance, 
of breathing impure air, or of other improper conditions 
of life. One class of very important diseases is pro- 
duced by parasitic animals or plants growing in the 
body. 

Some diseases we say are " catching," by which we 
mean that one person very readily gets the disease from 
another. This class includes such diseases as measles, 
scarlet fever, mumps, whooping cough, etc. Such dis- 
eases are called contagious. Another class of troubles, 
like rheumatism, malaria, etc., are non-contagious, since 
healthy persons do not " catch " them from sick people. 

PARASITIC DISEASES 
Contagious diseases are probably all caused by very 
small animals or plants that get into the human body 
and multiply there. Most of them are so small that 
they can be seen only with the aid of a very powerful 
microscope. 



HEALTH AND DISEASE 239 

Parasitic Animals. — There are a few animal parasites 
that occasionally get into our bodies and cause trouble. 
One of these is the tapeworm, which enters the body 
from raw or insufficiently cooked beef or pork. It lives 
in the intestines and makes considerable trouble, al- 
though it is not usually very dangerous. Another such 
parasitic animal is the trichina, which also comes from 
eating pork, not properly cooked, such as rare or 
slightly cooked ham or sausage. The disease resulting 
is violent and painful, and often causes death. The 
simple method of avoiding both tapeworm and trichina 
is to eat no meat that is not thoroughly cooked. 

Another form of animal parasite produces malaria, or 
chills and fever. This parasite is a minute animal, to 
be seen only through a microscope, which gets into the 
body, usually from the bite of the mosquito. Certain 
kinds of mosquitoes are liable, when they bite, to leave 
in the skin some of these little parasites. The best 
way to protect ourselves against malaria or chills and 
fever is to keep from being bitten by mosquitoes. 
This may be done generally by covering the doors and 
windows of our houses with mosquito netting, particu- 
lar care being taken to remain behind such netting at 
night. 

Parasite Bacteria. — The most important of the para- 
sites that make their way into the body are a type of 
plant called bacteria. These minute plants are so small 
that a powerful microscope is required to see them, and 
so light that they can easily float around in the air in 
the form of dust. They are very abundant everywhere. 



240 PHYSIOLOGY AND HYGIENE 

Some of them, instead of being harmful, are directly 
useful to us. Bacteria cause the souring of milk and 
the decay of meat ; they produce vinegar and the flavor 
of butter and cheese; and they prepare the soil for the 
growth of plants. These tiny parasites are, on the 
whole, very useful friends of ours. 

But while some bacteria are healthful, others, which 

may live as parasites in our bodies, produce certain 

• % diseases. Some of these 

iv' are shown in Figure 

/r, o j * 79. Typhoid fever, con- 

j If CnO/tra ^§i$J> sumption (tuberculosis), 

"^/ , n:AJt • diphtheria, and boils and 

Tubtrculosb ^J'^ 61 '' Jseeuesoi the skin are 

iyphoid^Sj{f> produced by them. 

Other contagious dis- 

^SoSxS^ eases, like measles, scar- 

O< *oooc» let fever, mumps, and 

Abscess whooping cough, are 

Fm. 79. -Bacteria that produce probab l y caused either 

Certain Diseases. 

by bacteria or by some 
other microscopic parasites. Each of the different dis- 
eases is produced by its own kind of bacteria. 

Protection against Harmful Bacteria. — Bacteria can- 
not ordinarily injure us unless they get inside the body. 
We have already seen how the skin forms a covering 
which protects the body from the entrance of external 
objects, and this commonly keeps out dangerous bac- 
teria. So well are we protected that the majority of 
them do no harm whatever, because they do not obtain 



HEALTH AND DISEASE 241 

entrance to the body. We need not be frightened, 
then, because bacteria are present in milk and water, 
for this is the natural condition. The bacteria in milk, 
and also those in water, are usually, though not always, 
harmless. 

Even if the bacteria of diseases do find their way into 
the body, it does not necessarily follow that they will 
effect injury. The human body is able to fight these 
bacteria, and in many cases to destroy them before they 
do harm. When we are in the best condition of health, 
our power of resisting them is greatest, and conse- 
quently we are then less liable to take some contagious 
diseases than when we are in a more or less weakened 
state. In general, the best method of avoiding all bac- 
terial diseases is to keep in robust health, although 
even perfect health apparently cannot protect one 
against taking some contagious diseases. Robust 
health, as we have seen, depends upon plain, whole- 
some food, plenty of fresh air and outdoor exercise, 
and living a regular life. 

Immunity from Contagious Diseases. — Many conta* 
gious diseases, such as smallpox, scarlet fever, mumps, 
chicken pox and yellow fever, are rarely taken by the 
same person more than once. In some way, which we 
do not fully understand, the first attack acts upon the 
body so that it is able to resist the action of the para- 
sites ever afterward. A person who has had one attack 
of such a disease is said to be immune to future attacks. 
Advantage is taken of this fact by vaccination, by which 
we are protected against smallpox. When vaccination 



242 PHYSIOLOGY AND HYGIENE 

" takes," it causes what is really much like a mild form 
of smallpox, which makes us for a certain time immune 
to that disease. 

Prevention of Contagious Disease. — The best way to 
check the spread of contagious diseases is to prevent 
the distribution of the bacteria that cause them. If we 
can keep these minute growths from passing from one 
person to another, we can frequently stay the spread of 
the disease. The rules adopted by the boards of health 
in our cities, especially in connection with schools, are 
made for the sake of preventing the spread of bacteria. 
That is why persons having contagious diseases, such 
as diphtheria, are placed in rooms by themselves. That 
is why children are not allowed to attend school when, 
for example, a member of the family has the measles. 
In general, the regulation of these matters may be left 
to boards of health, but there are a few facts which it 
is well for us all to understand. 

How Bacteria get out of the Body. — When a conta- 
gious disease is "taken" from a person by another, 
the bacteria which produce the disease must have 
passed from the body of the patient to that of the other 
individual. Usually, the bacteria pass from the body 
of the sick person in some of the secretions or excre- 
tions. If the disease is accompanied by sores, such 
as boils, the bacteria leave the body in the discharges 
from the sores. If there is an eruption from the 
skin, as in scarlet fever and measles, the bacteria prob- 
ably leave the body from the skin, as well as from the 
discharges of the mouth and nose. If there is a dis- 



HEALTH AND DISEASE 243 

charge from the digestive canal, as in typhoid fever, 
bacteria find exit with what passes from the bowels. If 
the disease is in the mouth or throat, as in diphtheria, 
bacteria will usually be found in the saliva. If it is 
in the lungs, as in consumption, we may look for the 
bacteria in the saliva and phlegm coughed up by the 
patient. If the disease is accompanied by a cough, as in 
whooping cough, we may regard the breath during the 
coughing as carrying the bacteria. 

How Bacteria are Carried. — 1. Many of the dis- 
charges from patients get into sewage through drains 
and closets. Hence the sewage of a city is almost sure 
to contain hosts of dangerous bacteria, and it should 
be disposed of in the safest and most careful manner 
possible. If it enters a river, and the water of the 
same river is used for drinking, many cases of typhoid 
fever are almost sure to arise. Most of the sewage of 
a city enters into common sewers, and each house is 
connected with these sewers. It is necessary, there- 
fore, to have means for preventing the bacteria in the 
sewers from entering the house. This is accomplished 
by properly devised plumbing. We can thus compre- 
hend the importance of having and keeping the 
plumbing of a house in good condition. 

2. Bacteria may be transferred by contact, either 
actual contact with a patient or with something that 
he has touched. A nurse may get bacteria upon her 
hands from handling the patient or his clothing. If 
she washes her hands frequently and refrains from put- 
ting her fingers to her mouth, the danger from conta- 



244 PHYSIOLOGY AND HYGIENE 

gion will be largely reduced. Other persons in the 
house may take a contagious disease by using spoons, 
knives, forks, cups, or saucers which have been em- 
ployed in the sick room. Bacteria cling to such arti- 
cles, and may thus be transferred to any person using 
the dishes. The danger may be avoided by allowing 
no one to use the same eating utensils as the sick per- 
son, or by washing them thoroughly in boiling water 
before they are used by others. Bacteria are also fre- 
quently left by sick persons upon door knobs, stair 
rails, etc., and these should, therefore, be carefully 
washed. In general, it is an excellent rule always to 
wash the hands before eating, and to avoid eating food 
which has been handled by others. 

3. Bacteria may be carried by the air. When the 
skin peels, as in scarlet fever, or when there is a skin 
eruption, as in smallpox, the germs probably pass into 
the air, and may thus be carried to other persons. The 
same is true of diseases with which there is a cough, 
such as whooping cough and consumption. It is not 
very easy to guard against this danger if we must stay 
in the same room with the patient ; but the danger may 
be reduced, as much as this is possible, by insisting 
upon a constant supply of fresh air in the sick room. 
The germs, after floating in the air for a while, settle 
with the dust. Every time the room is swept or dusted 
they are stirred up again. Sweeping and dusting 
schoolrooms increases the chance of the spread of con- 
tagious diseases. So far as possible, wiping with damp 
cloths should replace sweeping and dusting. After the 



HEALTH AND DISEASE 245 

bacteria have reached the out-of-door air, most of them 
are killed by the sunshine, although this is not true of 
the bacteria of all diseases. 

4. Uncooked food sometimes distributes disease bac- 
teria. This applies chiefly to water and milk. Water 
from a river receiving city sewage is the most common 
source of typhoid fever. Milk is occasionally the source 
of diphtheria, scarlet fever, typhoid fever, or diarrhoea. 
In case of epidemics from water, we may protect our- 
selves by having the water boiled before we drink it. 
The only protection against disease carried by milk is 
either to buy the milk from reliable sources or to boil 
it before it is usedo Other foods which we eat un- 
cooked, such as lettuce, celery, raw oysters, and fruit, 
are occasionally sources of disease. Cooking is an 
efficient safeguard against the danger. 

5. Occasionally flies or other insects may carry 
disease germs, particularly those of cholera, typhoid 
fever, and some eye diseases. The chief precaution to 
be taken is, as far as possible, to prevent flies from 
alighting on our food or eating utensils. We have 
already learned that mosquitoes distribute malaria, 
and it is also true that they carry yellow fever. 

Every one should bear in mind a few simple rules 
which, if followed, will help to prevent the spread of 
contagious diseases. They are particularly important 
in schools where children from many families are 
brought together. 

Do not spit on the floor or sidewalk. 

Do not put pencils or penholders into the mouth. 



246 PHYSIOLOGY AND HYGIENE 

Do not put the fingers in the mouth. 

Do not put money in the mouth. 

Never put into the mouth anything that another per- 
son has had in his mouth (gum, bean blowers, whistles, 
drinking cups, etc.). 

When coughing turn the face away from others, and 
avoid allowing others to cough in your face. 

Wash the face and hands often. 

By these means we may largely avoid the germs 
which might get into our bodies. 

THE USE OF ALCOHOL 

We have learned in previous pages that alcoholic bev- 
erages are quite unnecessary to health, and are in many 
cases extremely harmful. They interfere to a large 
extent with the perfect health and happiness of man- 
kind. The question might naturally be asked, Why is 
it that people learn to use alcoholic beverages when 
these are not only of no use, but liable to do so much 
injury ? There are three main reasons : — 

(1) The boy does not realize the risk he is running. 
He does not expect that he will become addicted to the 
use of alcohol in such a way as to injure him. Com- 
monly he does not know the danger that lies before him, 

(2) The boy sometimes knows well enough that 
alcohol is dangerous and likely to do him harm, but 
he thinks it manly to drink, and is afraid of being called 
odd or priggish if he does not. But it is not manliness 
that causes a boy to follow his companions into a 
saloon. On the contrary, it is usually cowardice. He 



HEALTH AND DISEASE 247 

is afraid that he may be laughed at. It is really the 
manly and courageous boy who dares to stay outside 
and to refuse to follow others into useless danger, and 
in the end his associates never fail to recognize and to 
admire his real courage and manliness. 

(3) The third reason is the desire to be social. The 
boy finds that his companions drink beer, and he feels it 
more social to follow their lead, even at the cost of some 
danger to himself, than to oppose them, especially if they 
are a little older than he. He should remember that 
the kind of sociability that leads to a saloon, or into 
any other useless danger, had better be shunned. There 
is companionship far pleasanter than that which comes 
through a glass of beer, and there are friends more use- 
ful than those who invite one to a saloon or urge one to 
join in a social glass. 

Reasons why Alcohol should be entirely avoided as a 
Beverage. — The only wise course is to let alcohol en- 
tirely alone. There are three important reasons for 
so doing : — 

(1) It will do us physical harm. It is impossible 
for any one to tell where the injurious effects begin, or 
to say how much he may use without harm to himself. 
Small quantities are liable to lead to larger ones, and 
the habit of using alcohol is apt to cause an appetite 
which will result in untold evil. The only safety lies 
in avoiding alcoholic beverages altogether. Many a 
person who seemed strong-willed has to his sorrow 
found his will power insufficient to resist the craving 
which alcohol has developed. 



248 PHYSIOLOGY AND HYGIENE 

(2) The constant use of alcohol, even in moderate 
amounts, frequently lowers one's moral tone and intelli- 
gence and thus interferes with one's chance of success. The 
parts of the city which show the greatest poverty are 
the parts which abound in saloons. Prisons are filled 
with men and women who have used alcohol. The use 
of alcohol not only means the waste of large amounts 
of money, but if continued, it has a tendency to reduce 
a person's chance in life. It frequently ruins ambition ; 
it tends to destroy the power of attending strictly to 
work; it makes a man careless about fulfilling his 
responsibilities, and is likely to lead to loss of employ- 
ment. Some corporations, especially railroads, refuse to 
put into responsible positions, such as those of engineers 
and switchmen, persons who use alcohol even " in mod- 
eration," or occasionally. It is not simply those who 
use alcohol in large amounts who risk their chances 
of rilling responsible positions. The use of alcohol is 
likely to bring a boy into a circle of acquaintances who 
will injure rather than benefit him. It is likely also, 
when he has become a man, to destroy his interest in 
his family and all that is good, and to lead him to live 
a life upon a low plane. 

(3) Our example will influence others. We all have 
some responsibility for those about us, and to lead 
another, by our example, into a course of life that in- 
jures him, is a very serious thing, the results of which 
we cannot measure. When people see their friends 
using alcohol, they are very likely to think that they 
can do the same. They may be led to use alcohol in 



HEALTH AND DISEASE 249 

excess from seeing others use it in moderation. The mod- 
erate drinker is the one whom others try to follow. He 
is thus in a measure responsible for the downfall of the 
friend who, weaker than himself, tries to follow his lead. 
The healthy person does not need alcoholic drinks 
and is better off without them. They always produce 
an abnormal mental condition. What is needed for the 
best success in life is a mind acting in its normal con- 
dition and uninfluenced by drugs, either by narcotics or 
stimulants. Alcohol always makes the mind's action 
unnatural and hence inferior to its natural action. This 
effect, in impairing the keenness of the mental action, 
is just as sure whether small or large amounts are used, 
though differing in degree. 

THE DUTY OF PRESERVING HEALTH 

It is our duty to make the most of our opportunities 
in life. Whether we decide upon a business career or 
a profession, we are sure to find that, in the sharp com- 
petition of to-day, a good body and abundant physi- 
cal health are wonderful aids in reaching the greatest 
success in life. Physical strength will give one power 
to become a leader among men. Failure to develop 
our powers to their highest extent will result in a life 
unsatisfactory to ourselves. It is our duty to set our 
ambitions high. There is no one who may not hope 
for success, and no one who should not endeavor to live 
a broad and useful life. The higher we aim, the higher 
the position we shall reach. It is perfectly right and 
honorable to determine to reach a responsible position 



250 PHYSIOLOGY AND HYGIENE 

in business, to acquire wealth and power, and to become 
a person of influence. These things are possible to 
every American youth who will make proper use of his 
opportunities. Without perfect health, however, suc- 
cess is likely to slip from the grasp. One of the best 
assurances for a successful life is a well-developed, 
active, healthful body. 

We should remember that the body is a marvelous 
machine. Its value depends upon its being in a condi- 
tion of the greatest efficiency. A locomotive with a leak- 
ing valve may still pull a few cars, but it is much less 
useful than a perfect engine. So our bodies, even when 
more or less out of order from abuse of one sort or 
another, may still keep alive and carry on some of the 
duties of life; but they will do less work than when 
they are in perfect condition. 

The value of the human body as a machine is lowered 
by every form of overindulgence. Excess in eating, in 
talking, in playing, or in working reduces our chances 
of future success. Immoderate eating and drinking 
injure digestion ; excessive talking destroys confidence 
in our statements ; too much play makes a boy unready 
for the more serious duties in life ; and too much work 
makes him tired and dull. The study of our body 
teaches that any kind of indulgence results in a general 
lowering of the powers of the bod}^ and mind, and makes 
us less capable of achieving the highest end in life. 

The study of these pages has resulted in showing 
that two great fundamental laws for developing a 
perfect body and living a useful life are : — 



HEALTH AND DISEASE 251 

(1) Use every power you possess. 

(2) Avoid the overindulgence of all appetites and all 
desires. 

QUESTIONS 

1. What is the purpose of medicine ? 

2. Why should medicine be avoided as much as possible? 

3. What causes most contagious diseases? 

4. What is meant by parasitic animals? 

5. How are tapeworms and trichinae taken into the human sys- 
tem? What is the result with each? 

6. How are malarial organisms taken into the body? 

7. How can the body best be protected against injurious 
bacteria? 

8. How may the spread of contagious diseases be prevented? 

9. How do the injurious bacteria pass from a person who has 
sores or boils? Scarlet fever or measles? Typhoid fever? 

10. In what important ways may bacteria be carried ? 

11. Why should plumbing be kept in good condition? 

12. How may bacteria be transferred through contact? 

13. How may bacteria be carried in the air? 

14. Why is wiping with a damp cloth better than dusting in a 
schoolroom ? 

15. How may bacteria in food be destroyed ? 

16. How can we reduce the danger of taking a disease dis- 
tributed by coughing? 

17. How may we prevent diseases being spread by insects ? 

18. WTiy should we have light and air in our sleeping rooms ? 

19. What three conditions most commonly lead a person to use 
alcohol as a beverage ? 

20. Why should alcohol be entirely avoided as a beverage ? 

21. What are the two fundamental laws of health and use- 
fulness ? 



CHAPTER XIV 
PREVENTABLE DISEASES 

We have learned that some diseases are " catching," 
or contagious, and that such diseases are caused by 
germs. By germs we mean minute living animals or 
plants, far too small to be seen without a microscope, 
but able to grow and multiply inside the body if they 
once get in. After they have become numerous in the 
body, they produce trouble that we call disease. If 
the germs get outside again and pass into the body of 
another person, they may produce the disease in him. 
For this reason we say that such a disease is contagious. 
A contagious disease is thus simply one that is caused 
by a living germ which is easily able to pass from a 
sick person to a healthy one. 

GERM DISEASES ARE PREVENTABLE 

People used to think of diseases as mysterious afflic- 
tions, sent, perhaps, by some angry demon. As long 
as they were thought of in this way, it was impossible 
to do anything to prevent them. But now that we 
know that diseases are caused by germs, know where 
the germs come from, how they are carried from the 
sick person, and how they get into the well person, we 
know how to fight them. In the few years since we 
have known that diseases are caused by germs, our sci- 

252 



PREVENTABLE DISEASES 



253 



entists have been learning better each year how to 
destroy them and prevent them from being scattered 
where they will do harm. As a result, the number of 
cases of illness and death from 
contagious diseases has been 
constantly diminishing. 

If these diseases are caused 
by germs that pass from the 
sick to the well, it will, of 
course, be possible to avoid 
them entirely if we can only 
find out how the germs are 
carried and then devise some 
means of preventing it. For 
this reason we call them pre- 
ventable diseases. Already 
we know so much about some 
of the contagious diseases that 
they could be largely, if not 
wholly, prevented :f people 
would only learn a few simple 
facts and follow a few simple 
directions. The methods by 
which tuberculosis can be 
fought are given in detail 
in Chapter XV, and most 
of our contagious dis- 
eases could in a similar way be largely prevented if 
it were only possible to get people in general to under- 
stand the facts. Without such knowledge people 




Fig. 80. — Comparative 
Diagram. 

The smaller figure represents the 
number of United States sol- 
diers killed by bullets as com- 
pared with the larger figure, 
the number killed by disease 
in the war with Spain. 



254 



PHYSIOLOGY AND HYGIENE 



will ignorantly come into contact with germs that 
they could easily avoid. Nothing is more important 

for health than to know the 
causes of the various preventable 
diseases and how to avoid them. 
The Lesson taught by the 
Japanese. — The whole world was 
given a lesson in the prevention 
of disease by the Japanese army 
during the recent war between 
Japan and Russia. In all pre- 
vious modern wars more soldiers 
have died of diseases than have 
been killed by bullets. But the 
Japanese had learned what the 
scientist had to teach about the 
methods of preventing the par- 
ticular diseases likely to appear 
in the army. They therefore 
sent their doctors and scientists 
ahead of the army, to find out 
the healthy and unhealthy places 
for camps, to learn whether the 
water of the streams and wells 
was fit to drink, and to discover 
any other things that might 
make the soldiers sick when 
they came to camp. The 
soldiers were told how important it was for them to 
obey the directions of these advance guards, since it was 




Fig. 81. — Comparative 
Diagram. 
The larger figure represents 
the number of Japanese 
soldiers killed by bullets, 
as compared with the 
smaller figure, the number 
killed by disease in the 
war with Russia. 



PREVENTABLE DISEASES 255 

just as much a matter of patriotism for them to keep 
well as it was to be brave in battle. The Japanese 
soldiers obeyed as no other body of men ever obeyed 
such directions, and this gave the world a chance to 
see what could be done if men generally would follow 
the advice given by the physician and the scientist. 
The result was most remarkable. In our own armies 
only four years before, during the war with Spain, for 
every one person killed by bullets four died of disease. 
In the Japanese army only one died of disease for every 
four that were killed by the enemy. Preventable dis- 
eases almost disappeared. What the Japanese army 
did other people can do, just as soon as they will listen 
to the scientific explanations of the distribution of dis- 
ease, and are willing to follow directions. 

THE SOURCE OF DISEASE GERMS 

Although all contagious diseases are probably pro- 
duced by germs, each disease is caused by a distinct 
type. Tiny as these germs are, they are of many 
kinds and many different habits, so that each one 
needs to be fought in its own way. Methods that are 
useful in preventing one disease are often of no use 
in preventing another. For this reason each disease 
must be studied by itself. 

In regard to the sources of disease germs, however, 
one general statement can be given. Disease germs come 
from the body of some person or some animal that has 
the disease. The disease germs do not, as a rule, live 
long anywhere outside the living bodies of men or 



256 PHYSIOLOGY AND HYGIENE 

animals. In some cases, however, they are able to 
remain alive for a short time after they leave the body, 
some kinds only a few hours, and others, several months. 
After they are dead they are no longer dangerous, but 
as long as they are alive we need to guard against 
them. Hence, although their real source is the sick 
person or animal, the germs may be scattered from him 
and reach a well person from some other source. With 
diseases like tuberculosis, where the germs can live for 
months outside the body, we have to guard against 
other sources of the germs besides the patient. 

It has been generally believed that disease germs fre- 
quently cling to clothing and are thus carried from a 
sick to a well person. While this is occasionally the 
case, the danger from this source is really slight, less 
than has been supposed. The secretions from the 
patient, faeces or sputum or discharges from the skin, are 
the great sources of danger, and if these are properly 
disposed of there is not much chance for the germs to 
adhere to clothing. It is extremely unusual for a person 
visiting a sick room to carry the germs in his clothing 
to another outside. 

In trying to learn how to avoid the disease germs we 
need therefore in each case to ask four questions : 

1. How do the germs leave the body of the 
patient ? 

2. How long can they live outside ? 

3. How are they carried to the well person? 

4. How do they get into the body of the well 
person? 



PREVENTABLE DISEASES 257 

DISEASES OF THE MOUTH AND RESPIRATORY 
ORGANS 

Diphtheria. — Diphtheria has been one of the most 
dangerous diseases, especially for children ; but fortu- 
nately scientists have learned so well how to prevent 
and to cure it that it is much less dangerous than it 
used to be. It usually begins with a sore throat and 
with whitish spots on the tonsils. The white spots 
spread, forming a membrane which grows down into 
the throat, and which contains great numbers of the 
diphtheria germs (Fig. 79, page 240). 

The way in which the germs injure the patient is 
this. Growing in the throat they secrete deadly poisons 
which are absorbed through the walls of the throat into 
the person's blood, and poison him. The body has, how- 
ever, a very remarkable power of producing a substance 
that neutralizes the effect of the poison. The poison is 
called a toxin, the neutralizing substance is an antitoxin. 
The germs make toxins, the body makes antitoxins. If 
the germs make toxins faster than the body makes anti- 
toxins the patient finally dies ; but if the body can 
make antitoxins fast enough to neutralize the toxins, 
he recovers. A few years ago scientists discovered a 
way to make animals produce this antitoxin for us. 
When a person has diphtheria the doctor gives him 
some of this antitoxin with the result that the toxins 
produced by the germs are neutralized quickly and the 
person almost invariably recovers if it is given early 
in the disease. For this reason the disease has become 
much less fatal than it used to be. 



258 PHYSIOLOGY AND HYGIENE 

Diphtheria is contagious because the bacteria adhere 
so loosely to the walls of the throat that they are easily 
detached. Then they get into the saliva, and will be 
sure to be left upon anything that the patient may 
have in his mouth: for example, his fingers, pencils, 
gum, drinking cup, knife, fork, spoon, etc. Another 
person using the same pencil or drinking cup may get 
the germs in his mouth, and may thus "catch" the 
disease. Even after a person has recovered from diph- 
theria, he usually carries the germs in his mouth for 
about three weeks, and during this time he may be the 
means of giving them to others. 

We can easily see how these germs may be carried 
from person to person in a family where there are 
several children, or in a school, especially when we 
know that they can remain alive for several days after 
leaving the mouth. Any object that has been in the 
mouth of a person who has recently had the disease 
may give the disease to another who puts it into his 
mouth. The best safeguard is, therefore, never to put 
into the mouth anything that another has had in his 
mouth, and to keep away as much as possible from per- 
sons who have sore throats. The health officer will see 
that sick persons are kept from school as long as they are 
capable of shedding the germs. Sometimes a person who 
is perfectly well may have the germs in his throat, and 
the germs, although not injuring him, would be danger- 
ous to another person. Hence it occasionally becomes 
necessary to keep out of school a pupil who is perfectly 
well, but who has the diphtheria germs in his throat. 



PREVENTABLE DISEASES 259 

Tonsilitis. — Tonsilitis is also accompanied by a sore 
throat and fever, but it is much less serious than diph- 
theria, usually lasting only a few days. The only 
means known for avoiding it is to keep away from 
those who are ill. The germ that causes it is not 
known, and we do not know how it is carried. 

Mumps. — Mumps is chiefly a disease of children, 
although grown people have it occasionally. The 
glands of the cheeks and jaws become swollen and pain- 
ful, and it is difficult to move the mouth to chew or 
swallow. To avoid it one must keep away from those 
who have the disease, and patients should be kept out 
of school until well. No one has yet discovered the 
germ that causes mumps or how it is distributed. 

Influenza or La Grippe. — The grip closely resembles 
a cold and is sometimes difficult to distinguish from 
one. It is certainly contagious, and the germ that 
causes it is sure to be in the mouth and nose, and in 
the sputum and discharges from the nose of the patient. 
These discharges should therefore be treated like the 
sputum of consumptives, received in cloths to be burned, 
boiled, or otherwise destroyed. Where possible the 
patient should be isolated from others, especially from 
old people, w r ho are most likely to take the disease and 
with whom it is most serious. The grip is more serious 
than a cold and sometimes its effects last for weeks. 
It occasionally leads to pneumonia by decreasing the 
person's resistance to the pneumonia germ. We know 
of no means to prevent it except by avoiding patients 
as much as possible and by keeping up the general 



260 PHYSIOLOGY AND HYGIENE 

health by good food, exercise, and especially by plenty 
of outdoor air. 

Pneumonia. — Pneumonia is a very serious disease of 
the lungs caused by a germ and not, as is sometimes 
supposed, by a cold. The germ is frequently found in 
the mouths of well persons, doing them no injury ; but, 
if the lungs become inflamed by a " cold on the lungs," 
the pneumonia germs may find a chance to enter at 
the inflamed places, thus causing the disease. For 
this reason a cold in the chest should be given par- 
ticular attention. 

Pneumonia is sometimes contagious, and several cases 
sometimes follow each other in a family. The sputum 
of the patient contains the germs and should therefore 
be carefully handled and burned or disinfected. The 
danger of contagion is, however, slight, but other mem- 
bers of the family should not be allowed to come into 
too close contact with the patient. The need of fresh 
air is greater in pneumonia than in any other disease, 
and sometimes people are enabled to recover from this 
disease by giving them pure oxygen to breathe. 

DISEASES ASSOCIATED WITH THE DIGESTIVE ORGANS 

Typhoid Fever. — Typhoid fever is one of the more 
serious preventable diseases. It is marked by a fever 
which continues for days and sometimes for weeks. It 
makes a person very ill and results in death in about 
one case in ten. Even when the person recovers, it is 
likely to leave him weak and unable to work for months. 
The cause of the disease is a bacillus (Fig. 79, page 240), 



PREVENTABLE DISEASES 261 

• 
that grows in the intestine in immense numbers and is 

passed from the body with the faeces. Sometimes it is 

in the kidneys and passes off in the urine. For another 

person to " catch " the disease, the germs must get into 

his mouth and be swallowed. Since the germs can pass 

from the patient's body only in the ways described, 

typhoid fever does not commonly pass directly from 

person to person, although it does sometimes. 

But the germs can remain alive outside the body for 
some weeks. Hence there are other indirect means by 
which they may reach a well person, and it is against 
these that we need especially to be on our guard. 

By water. — If the excretions from a patient are 
thrown upon the ground they may be washed into a 
well (Fig. 93). If they are put into closets they pass 
into the sewers and hence into a stream or the ocean. 
In each case the water will be contaminated with the 
germs, which will remain alive and ready to do mischief 
for about six weeks. The water from such wells or 
streams is unfit to drink. Clearly, then, we should 
carefully protect water from all sewage. If it should 
be necessary to use, for drinking, water that has the 
slightest opportunity for being mixed with sewage, the 
water should be boiled in order to kill the germs and 
render them harmless. 

By milk. — Sometimes a milkman washes his milk 
cans in water from a well or a stream, and if the water 
is contaminated with sewage, the typhoid bacilli may 
thus get into the can. The germs will then grow in 
the milk and people drinking it may take the disease. 



262 



PHYSIOLOGY AND HYGIENE 



Hundreds of cases have been known to appear in a city 
almost at once, as the result of a single day's contami- 
nated milk. The only absolute safety against this is to 
kill the germs by pasteurizing the milk (^heating it to 
about 150° F. for a few minutes). 

By flies. — Flies may feed upon the faeces of typhoid 
patients if exposed to the air, and while doing so they 

will be sure to get the 
germs upon their feet. 
Then, if they fly into our 
dining rooms and light 
on our food or eating 
utensils, they may leave 
the germs so that we 
swallow them when we 
drink or eat. It has 
been urged that the 
house fly should be called 
the "typhoid fly," to 
keep ever before us its 
dangerous power in this 
respect. Keep flies out 
of the house and away from all food or eating 
utensils. 

By oysters and shellfish. — Oysters and clams grow- 
ing near the outlet of sewers may become contaminated 
with the typhoid germs. If they are afterwards eaten 
raw, the living germs may be taken into the stomach. 
If the oysters are cooked, there is no danger. 

Hook Worm Disease. — Hook worm disease, as our 




Fig. 82. — The Common House Fly. 



PREVENTABLE DISEASES 



263 



scientists have recently found, affects many people in 
the southern states. It is caused by a tiny worm that 
lives in great numbers in the intestine. The patient 
does not realize that he is ill, for the disease simply 
makes him weak and indolent; and 
his friends perhaps think him lazy, 
when he is really an invalid. 

The disease is chiefly associated with 
and chiefly acquired from filthy hab- 
its. The eggs of the worms pass out 
of the body with the fasces and de- 
velop into little worms too small to be 
seen by the eye. These remain alive 
on the ground and are likely to catch 
upon a person's bare feet. Here they 
first cling to the skin and later bore 
their way through into the blood vessels 
and finally into the intestine. Most 
cases of the disease are thus due to 
filthy habits and bare feet, although 
there are other means by which the 
worms may get into the intestine. The 
disease may be largety avoided by clean- 
liness and by wearing shoes. 

Cholera. — Cholera is a germ disease 
that has been common in some eastern 
countries, but hardly known in the United States. 
Since it was discovered that the germ is distributed by 
contaminated drinking water, the disease has almost 
entirely disappeared from Europe. 




Eig. 83. — The 
Hook Worm. 
a, natural size, 
ft, an adult worm, 

magnified, 
c, a young worm 
ready to enter 
the body through 
the skin. 



264 



PHYSIOLOGY AND HYGIENE 




DISEASES OF THE BLOOD 

Malaria. — Malaria, chills and fever, fever and ague, 
are all the same disease and are caused by tiny parasites 
that live in the red corpuscles of the blood. 

The disease is 
found all over 
the country, 
though it is less 
common and less 
serious in the 
northern than in 
Fig. 84. — Anopheles, the southern 

The mosquito that distributes malaria. states. Its most 

common symptom is the appearance of a chill followed 
by a fever, and then a period in which the person feels 
better, though he soon has another chill with its fever. 
These periods follow with 
regularity every two days 
as a rule, though sometimes 
every day or every three 

da y S ' t m Fig. 85.-Culex. 

The disease is especially The common mosquito. It does 

common around swamps, not carry malaria. Note that it 

and it was formerly thought assumes a different posture from 

- , ,,. that of Anopheles (Fig. 84). 
to come from breathing 

the damp air, especially the night air of infested locali- 
ties. We now know that the air itself is not danger- 
ous, but that the disease is spread only by the mos- 
quitoes that may be in the air. Only one kind of 




PREVENTABLE DISEASES 265 

mosquito is to blame, and this one not unless he has 
previously bitten some one who has malaria. If this 
kind of mosquito, that is called Anopheles, bites a person 
who has the disease, it sucks the blood with the germs 
into its body. If the same mosquito later bites a well 
person, it may inoculate him with the germs that have 
grown from those in the blood of the first patient. 

Now that we know this fact we can prevent malaria, 
if we can protect ourselves against mosquito bites. 
Mosquito nettings at windows and doors are a good 
protection against the disease, and the destruction of 
the breeding places of the mosquitoes is even better. 
Mosquitoes breed in pools of stagnant water and, if 
these are filled up or drained, the mosquitoes disappear. 
A little kerosene put on the surface of such pools will 
spread rapidly and smother the mosquito young. 
Barrels and cisterns of rain water also furnish good 
breeding places. As fast as the mosquitoes disappear, 
malaria disappears also. 

It is important to remember that the malaria mosquito 
only flies at night. This is doubtless the reason why 
people have believed so long that night air is unwhple- 
some. But if we only get rid of mosquitoes, night air 
is not injurious, and if we use mosquito nettings we may 
keep the windows open all night without fear. 

Yellow Fever. — Yellow fever is another disease dis- 
tributed by mosquitoes, but we do not yet know 
whether it is a disease of the blood. The disease is a 
very serious one and is generally fatal. Fortunately, 
it is not common in this country, being found chiefly in 



266 



PHYSIOLOGY AND HYGIENE 




warm, tropical climates. Occasionally it has invaded 
our southern states, producing frightful epidemics and 
killing thousands of people. A few years ago three 

scientists went 
to the warm cli- 
mates to study 
the disease. 
Thinking that it 
was carried by 
Fig. 86.— Stbgomtia. mosquitoes they 

The mosquito that distributes yellow fever, allowed them- 
selves to be bitten by mosquitoes that they suspected, 
and one of them took the disease and died of it. He 
was a hero, just as brave as one who fights in battle, 
and his death has been one of the great benefits to 
mankind, for it has shown us 
how to stop this frightful 
disease. 

To fight the mosquito is to 
fight yellow fever. It is not 
the common mosquito that is 
to hlame, nor is it the same 
one that carries malaria. To 
stop yellow fever the breeding 
places of mosquitoes should be 
destroyed, or covered, to pre- Fig.V -The Flea (greatly 
vent mosquitoes from getting magnified), 

into them to lay their eggs. The patient, too, is to be 
guarded from mosquitoes, since it is only by biting a 
patient that the insect obtains the germs and can thus 




PREVENTABLE DISEASES 



267 



carry the disease. For this reason, yellow fever 
patients are now kept carefully covered by mosquito 
netting, so that the insects cannot bite them. 

Since this way of fighting yellow fever has been 
followed, the disease has lost most of its terror. In 
Havana, and in Panama, where yellow fever was always 
found before this discovery, it has now almost dis- 
appeared. One epidemic in New Orleans, which started 
before the people understood the danger of mosqui- 
toes, was quick- 
ly stopped when 
they began to 
fight m o s q u i- 
toes. 

The mosquito, 
then, proves 
itself a deadly 
enemy, since it Fig. 88. — The Rat. 

is the means of This animal is largely responsible for the dis- 
distribu ting two tribution of the bubonic plague. 

most serious diseases. Money spent in its extermina- 
tion is well invested, and every one should be glad to 
aid in the work of destroying it. 

Bubonic Plague. — The plague is another disease that 
is distributed by the aid of insects. In this case it is 
usually the flea that gives it to man by biting him. 
The flea usually gets the infection from rats. To pre- 
vent the plague, therefore, the best plan is to kill all 
rats. This disease is very common in India, but has 
appeared in this country in a few instances. 




268 PHYSIOLOGY AND HYGIENE 

DISEASES ACCOMPANIED BY A SKIN ERUPTION 

Scarlet Fever, Measles, Chicken Pox. — We notice scar- 
let fever, measles, and chicken pox together, not because 
they are really alike, but because they are all accompa- 
nied by the appearance of blotches or colored spots on 
the skin, and because we have to follow the same means 
for prevention. Scarlet fever and measles are apt to 
produce severe, sometimes fatal, illness, while chicken 
pox is never serious. The germs that cause these dis- 
eases are not yet known, but the infection probably 
passes from the skin of the patient. 

It is particularly hard to guard against a disease that 
is spread by skin eruptions, and for this reason these 
diseases are very contagious. The only method of avoid- 
ing their spread is by keeping the patient from associa- 
tion with others, who are liable to take the disease, until 
the time is passed when he can convey the infection to 
others. The time that he must be thus quarantined 
varies in the different diseases from two to six weeks. 
It is sometimes hard to keep a child separated from his 
playmates so long after he has quite recovered from his 
illness, but this is' the only way to prevent the spread of 
the disease. Most towns and cities have regulations 
planned to prevent these diseases from spreading from 
scholar to scholar and becoming epidemics in the schools. 

Smallpox. — Smallpox is one of the most dangerous 
diseases, and in former times was a frightful scourge, 
causing an immense number of deaths. To-day it is 
much less common than it used to be, and has come to 



PREVENTABLE DISEASES 269 

be placed in the class of preventable diseases. The 
method of fighting it involves two factors : (1) isolation 
of the patient from well persons, and (2) vaccination. 
In countries where vaccination is enforced by law the 
number of cases of smallpox is low. In order that im- 
munity be lasting, however, a person should be revac- 
cinated, since the effect of a single vaccination lasts only 
a few years. Doctors who have to treat smallpox 
patients are themselves vaccinated every few years, and 
are thus made immune so that it is safe for them to visit 
patients. If every one would take this precaution, 
smallpox would probably disappear entirely. 

MISCELLANEOUS PREVENTABLE DISEASES 

Boils, Abscesses, Inflammation, Erysipelas, Blood 
Poisoning. — Every one is familiar with the sores, some- 
times small and sometimes large and painful, called 
boils and abscesses. Most people, too, have learned by 
experience that if one cuts or bruises himself the 
wound sometimes becomes red and painful after a 
few days, and we say it is inflamed. Probably, too, 
we have all heard of cases of erysipelas and of blood 
poisoning which make persons very ill and sometimes 
produce death. 

Although these troubles seem very different, they 
are all produced by the same kind of germs (Fig. 79). 
These germs are about us at all times, on our clothes, 
on our hands and faces, in our mouths, etc., but com- 
monly they do no harm. They cannot trouble us as 
long as they are simply in the mouth or on the skin, 



270 PHYSIOLOGY AND HYGIENE 

and to do us any injury they must get through the 
skin into the blood or lymph within. If the skin is 
broken, bruised, or even scratched, they may get in and 
grow, causing inflammation, a boil, or some form of 
blood poisoning. If we can keep them out, we shall 
prevent this kind of troubles. All wounds, cuts or 
bruises, and scratches also, should therefore be care- 
fully cleaned. Use for this purpose only perfectly 
clean water. Better still, wash the wound with an 
antiseptic solution, like a weak solution of carbolic 
acid (one part to twenty), which will destroy the germs. 
If one will only keep on hand such a carbolic solution 
or some antiseptic ointment, and get into the habit of 
washing all cuts and scratches with it he will prevent 
many a troublesome sore, and ward off possibly some 
severe cases of blood poisoning. 

The condition of one's general health is one of the 
most important factors in warding off trouble from 
skin wounds. For if the body is in a good healthy 
condition, it has considerable power of resisting these 
particular germs, so that even after they get in through 
the skin they do not succeed in growing. If a person 
by improper life allows his general health to be injured, 
this power of resistance becomes so slight that every 
scratch he has becomes inflamed, and he may have one 
boil after another. We then say that the blood is "in 
bad condition." The fact is that the body in general 
has lost much of its power of resisting the attack of germs 
that may get in through the skin. To avoid this, one 
needs simply to follow the general laws of good health: 



PREVENTABLE DISEASES 271 

by eating good, wholesome, and not too rich food, 
taking plenty of exercise in the open air, getting proper 
sleep, and abstaining from alcohol and tobacco. 

There are certain kinds of wounds that need particu- 
lar care : 

Punctured wounds are produced by sharp instruments 
that penetrate the flesh, like nails, needles, bits of glass, 
splinters, etc. These wounds do not bleed much and 
appear less serious than a surface wound that bleeds 
profusely. But this makes them more likely to be 
troublesome. The object that produces such a wound 
should be removed, aud this is sometimes difficult when 
a piece of glass or a long splinter is imbedded in the 
flesh. But as long as the object remains there is likely 
to be trouble. The wound should be made to bleed 
freely so that the stream of blood shall wash away any 
dangerous germs that may be thrust into the flesh. 
Then the wound should be carefully cleaned with car- 
bolic acid solution, if possible, some of it being squirted 
into the wound. If the wound is a deep one it should 
have the care of a physician. 

Tetanus, or Lockjaw. — A wound made by a dirty 
object, like a rusty nail or a sliver of wood lying on 
the ground, is likely to be more dangerous than any 
other kind. This is because in some parts of the world 
there is in the earth a deadly germ which, if it gets into 
the flesh, may produce lockjaw, or tetanus. The rea- 
son why wounds from toy pistols, which are so common 
on Fourth of July, are particularly dangerous is because 
the boy's hands are apt to be dirty at the time, and any 



272 PHYSIOLOGY AND HYGIENE 

dirty object may have some of these germs clinging to it. 
Lockjaw that comes from these wounds is a very pain- 
ful disease and always fatal, so that the only way to 
fight it is to prevent it. This is one of the chief reasons 
why exceptional care should be taken to clean a punc- 
tured wound. 

Wounds made by fishhooks are troublesome, since it is 
sometimes difficult to remove the hook because of its 
barb. They are usually quite shallow, and frequently 
the easiest thing to do is to push the point through 
the skin and then cut off the point with the barb by 
means of a wire cutter, when the hook can easily be 
removed. 

Particular caution is necessary against playing with 
sharp objects like knives, scissors, button hooks, etc., 
and particularly against running with them in the 
hands or in the mouth. Many a serious accident re- 
sulting in the loss of a limb or of the eyes has resulted 
from such habits. 

Cuts and bruises on the feet should be handled more 
carefully than wounds elsewhere. This is because one's 
stockings are apt to be moist with perspiration and warm 
from the body heat so that germs find in them a very good 
place to grow. The stocking gets filled with troublesome 
germs, which inside the shoe come in constant contact 
with the wound, getting every opportunity to inocu- 
late the flesh through any break in the skin. For this 
reason serious sores are apt to start with a corn, or a 
little broken skin around the toe nail, and all cuts, 
bruises, and scratches on the feet should be carefully 



PREVENTABLE DISEASES 273 

cleaned, washed with an antiseptic solution, and then 
covered with clean cloth before the stocking is replaced. 
This habit will prevent many a sore toe and, perhaps, 
some serious case of blood poisoning that might result 
in the loss of a foot. 

Bites of animals are more dangerous than ordinary 
wounds because in an animal's mouth there are very 
likely to be dangerous germs, which will be pretty 
sure to be inoculated into the wounds made by his 
teeth. Inflamed wounds and blood poisoning are there- 
fore more apt to follow than with ordinary wounds. An 
antiseptic wash should never be omitted in such cases. 
The bites of dogs are sometimes especially dangerous, 
since they may produce hydrophobia. 

Rabies, or Hydrophobia. — Rabies is one of the most 
painful of diseases, but fortunately it is not only rare 
but preventable. When it occurs, it is always fatal. 
It is commonly acquired from the bite of dogs that are 
mad, or rabid. It should be remembered, however, 
that the disease is very rare among dogs and that a 
large proportion of dogs who bite are not mad at all, 
and their bites are no more dangerous than the bites 
of other animals. Many times a dog will bite boys 
who are tormenting him and will then be called mad. 
It is not difficult for a skilled physician to determine 
whether a dog is really rabid. If the dog is actually 
rabid, he will die in a day or two, and, after his death, 
an examination of his brain will tell at once whether 
or not he was rabid. It is, therefore, best not to kill 
at once the dog who has bitten people, but to keep him 



274 PHYSIOLOGY AND HYGIENE 

confined to see if he dies ; for if he does not die it is not 
a real case of rabies. 

If one is bitten by a dog that is really rabid or is 
strongly suspected of being so, the person bitten should 
be taken at once to a Pasteur Institute, where he can 
have a treatment that will, in almost all cases, prevent 
the development of the disease. It is necessary to pro- 
ceed quickly, however, since if the disease once gets 
started there is no cure for it. 

Rabies could soon be stamped out entirely if people 
would only consent to muzzling all dogs that roam 
about the streets. In countries where the law requires 
this precaution the disease is practically unknown. 

Whooping Cough. — Whooping cough is a germ dis- 
ease whose chief symptom is a violent cough which 
usually lasts several weeks. A bacterium has been dis- 
covered which probably causes the disease, but we do 
not surely know how it is carried from person to per- 
son. It is certainly contagious, and the contagion is 
greatest at the time when the patient is coughing. 
The germs are in the sputum and are passed from the 
mouth or nose with the breath during a coughing fit. 
The only protection is to avoid being close to patients 
while they are coughing. Life in the open air is the 
best thing both for the patient and for others who wish 
to avoid the disease. As long as the cough continues, 
the disease remains contagious. 

Pink Eye and Trachoma. — Pink eye is an inflamma- 
tion of the thin membrane that covers the eyeballs and 
lines the lids. While temporarily painful and weaken- 



PREVENTABLE DISEASES 275 

ing to the eyes, it does not last more than a few 
days. 

Trachoma, or granulations, is a more serious disease 
of the eyes and may sometimes produce blindness. It 
is a roughness on the eyeball or eyelids that makes one 
feel constantly as if dirt particles were in the eye. Both 
of these diseases are contagious and probably caused by 
germs. Towels, napkins, or handkerchiefs that have 
been used to wipe the eyes or face of a person having 
one of these diseases are sure to become infected with 
the germs and may cause the disease in another using 
them. For the protection of the eyes, as well as for the 
purpose of preventing the spread of some other diseases, 
the use of a common towel in schools, factories, and other 
public places should be abandoned. 

IMMUNITY AGAINST GERM DISEASES 

In the case of most germ diseases, if a person has 
the disease and recovers, he is for a time protected from 
a second attack. We say he is immune. The length of 
this immunity is not alike for all diseases. It lasts for 
years, or sometimes for a lifetime, in the case of small- 
pox, scarlet fever, chicken pox, yellow fever, whooping- 
cough, measles, and mumps. It lasts a much shorter 
time in the case of typhoid fever, malaria, diphtheria, 
grip, and tonsilitis, so short in some cases that there 
hardly seems to be any immunity at all. It will be 
seen therefore that if one has a disease in the first list 
above, he is very unlikely ever to take it again, and does 
not need for himself to take special precautions against 



276 PHYSIOLOGY AND HYGIENE 

contagion. Such persons are best for nurses, since they 
are not likely to take the disease from the patient. But 
a person who has had one of the diseases in the second 
list may, after a few weeks or months, take it again. 

QUESTIONS 

1. What is a contagious disease ? 

2. What is the chief source of disease germs? 

3. What are the methods by which diphtheria is carried from 
person to person ? 

4. How is the grip distributed ? 

5. How is pneumonia distributed? 

6. Give all the methods by which typhoid fever is distributed. 

7. What diseases are distributed by mosquitoes, and how may 
this be prevented ? 

8. How may we guard against diseases which have a skin 
eruption ? 

9. What precautions should we adopt to prevent inflamed 
wounds and blood poisoning ? 

10. Why are the bites of animals more dangerous than ordinary 
wounds? 

11. What is the cause of lockjaw? 

12. Why should the use of common towels not be allowed in 
public places? 

13. What is immunity? 



CHAPTER XV 

A WAR FOR THE NATION 

Every boy and girl who has studied American history 
knows how important it is, when a battle is to be fought, 
for each army to find out as nearly as possible how many 
men the other side has, how many cannon, and all that 
can be learned about the strength or weakness of the 
enemy. The side that does not take these precautions 
risks defeat in the struggle. 

CO 

So in the great war for the health of the nation, 
which is now being waged, we must first of all study 
the nature and resources of our enemy. 

TUBERCULOSIS 

It is not, as a rule, a good thing to think very much 
about diseases. We should think rather of how to 
make our bodies strong and keep them so ; and then, in 
case the germs of disease attack us, we shall have the 
very best means of defense. 

What We Have to Face. — There is, however, one 
disease, the most widespread and deadly of any known 
to man, which, if we all knew its causes and how to 
guard against it, might perhaps be entirely stamped 
out. We surely should be eager to learn everything 
that we can about it, so as to save ourselves and others 
from its attacks. 

277 



278 



PHYSIOLOGY AND HYGIENE 




This terrible disease is tuber- 
culosis, which we generally hear 
spoken of as consumption. 

"When we study about our Civil 
War we are shocked at the terrible 
loss of life in battle, yet the number 
killed in battle during that entire 
war was not as great as the 
number of those who die 
from tuberculosis in the 
United States every year. 
Is it not true, then, that 
our nation is in great 
danger and that we 
should study how 
best to defend it ? 

The Hopeful Side. 
— This would be a 
terrifying picture in- 
deed if there were 
not a hopeful side, 
which depends, how- Fig. 89. — Diagram Illustrating the 

ever, upon every man ^ EATHS DuE T ° F ° UR YEARS m 0F ClvIL 
, A _ War and Deaths Caused by Tubercu- 

and woman and boy L0SIS F0R igoo-04 Relatively Compared. 
and girl throughout 

the country knowing the danger and doing his share 
to overcome it. 

CONSUMPTION NOT HEREDITARY 
The Tubercle Bacillus. — Until very recently tuber- 
culosis, or consumption, was considered a hereditary 



A WAR FOR THE NATION 279 

disease, which could neither be prevented nor cured, 
and against which it was therefore useless to fight. 
The causes were unknown, and no medicine could be 
relied upon to effect a cure. 

But not many years ago it was discovered that 
tuberculosis is caused by a small plant called tubercle 
bacillus, so small indeed that it can be seen only with 
a microscope. Since this plant may be breathed in 
with the dust in the air, it is most often found in the 
lungs, though it may attack other parts of the body. 

The discovery of this tiny bacillus proved first of all 
that the disease cannot be inherited, because it would 
be impossible for a plant organism of this kind to be 
passed on from parents to children. A child might 
appear to inherit the disease when, as a matter of fact, 
the disease was " caught" while the child was very 
young from its mother or some one else in the family 
who was ill with it. 

CONSUMPTION CAN BE PREVENTED 

Disease Spread by Contact — Then, the discovery and 
study of this bacillus also showed that the disease can 
be prevented. No one can have consumption unless 
he in some way, directly or indirectly, comes in con- 
tact with a person who is a consumptive; and even 
then, if proper care be taken to prevent contagion, or 
if his body is in good condition, he is in no danger. 
But people do not, as a rule, know how to take the 
proper care, and that is the reason why the disease is 
so widespread and so dangerous. 



280 PHYSIOLOGY AND HYGIENE 

How the Bacillus Travels. — The common means by 
which the bacillus leaves the body of the sick per- 
son, if the disease is in the lungs, is by means of the 
" spit," or sputum, as it is more properly called, which 
is the matter coughed up from the diseased lungs. If 
this is allowed to soil the hands or clothes of the 
patient, or articles used by him, or if allowed to dry 
upon the floor so as to become powdered and mingle 
with the dust, anyone who comes into the room may 
get the bacteria on his hands and so into his mouth, or 
may breathe them into his lungs. Then, if the condi- 
tions are favorable, the disease develops. 

For those who come in contact with a consumptive 
iu this manner, we shall explain in the section on 
" Precautions for Consumptives " how all danger from 
direct contact with a patient may be avoided. 

The Crime of Spitting. — But it is by indirect contact 
that the disease has been spread so widely, and this 
is brought about by the filthy and unnecessary habit 
of spitting upon the floors or walls of a room, upon 
sidewalks, or in cars and other public places. Each 
bit of phlegm, or sputum, deposited in this way, may 
contain thousands of bacteria, and when the sputum 
becomes dry it flies about in the air as dust, and is 
breathed in by everyone in the vicinity. It would 
not be strange if among a number of people present 
anywhere there should be some whose bodies were in 
a more or less weakened condition from one cause or 
another; and so the disease is continually finding new 
victims. 



A WAR FOR THE NATION 281 

It is safe to say that if all spitting about rooms or in 
public places, or anywhere but in vessels provided for 
the purpose, could be done away with, we should have 
gone a long way toward stamping out the disease of 
tuberculosis. 

And when we consider that this simple precaution, 
with proper care of the people who actually have the 
disease, would result in the saving of thousands of lives 
in our own country every year, it is clearly worth our 
while to do all that we can to help bring this about. 

SOME WONDERFUL RESULTS OF THE STRUGGLE 

The actual results of the war against this disease in 
places where the people have been taught the facts 
about it that are given in this chapter, and have worked 
together to stamp it out, have been marvelous. 

In Maine, where pamphlets giving such facts and 
simple rules and precautions were distributed through- 
out the State, the number of deaths from consumption 
decreased from 1,352 in 1892 to 901 in 1903 — a decrease 
of from 20.24 per cent, of deaths per 10,000 inhabitants 
to 12.97 per cent, for the same number. 

In the two largest boroughs of New York City, where 
the most vigorous fight is being carried on, the death 
rate from pulmonary tuberculosis has decreased from 
4.27 per cent, in 1881 to 2.29 per cent, in 1903, though 
during the same time the population has greatly in- 
creased. 1 

1 These figures are given for 1903 because some special circum- 
stances affected the comparative death rate of the later years, which 
would require too much adjustment and explanation. 



282 PHYSIOLOGY AND HYGIENE 

CONSUMPTION CAN BE CURED 

The third important result of the discovery of the 
tubercle bacillus and its nature is the knowledge that 
consumption is not at all a hopelessly fatal disease, but 
can be cured if taken in time and treated in the proper 
way. Everyone ought to know about this, so that 
even if he does not need the information for himself, 
he may be able to tell others who do need it. 

Dangers from the Bacteria. — For the protection of 
others, as well as of the patient himself, the sputum 
should be destroyed immediately by being coughed 
into paper napkins which can be burned, or into cups 
containing a weak solution of carbolic acid or some 
other sterilizing material; these cups should be washed 
frequently with hot water and strong soap or lye. It 
is better not to use handkerchiefs or cloths; put into 
the pocket, they will soil the clothes. The hands and 
mouth should be washed very frequently in warm water 
and soap. As the saliva or the small drops of moisture 
coughed or sneezed out may contain the bacteria, equal 
care should be taken to cover the mouth and nose with 
a paper napkin, and thus prevent the distribution of 
the bacteria in this way. 

The patient may, by taking these precautions, effect- 
ually guard against spreading the disease among those 
with whom he daily comes in contact. In fighting 
the tubercle bacillus, the patient should take every 
precaution to prevent the possibility of new growths 
developing in his own system, as well as to use such 
preventive measures as he can, to avoid distributing 
the disease among others. 



A WAR FOR THE NATION 



283 



Special directions with regard to articles that are 
convenient for use will be given under " Precautions 
for Consumptives." 

Importance of Fresh Air. — First, the patient must 
have all the fresh air possible, night and day, summer 
and winter. The air should be in circulation, and with 
warm clothing and something wrapped about the head, 
no one need be afraid of " draughts." There must be 
draughts, that is, 
currents of air, in 
order to keep the 
air absolutely 
pure and to ensure 
the large supply of 
oxygen needed. 

If possible, the 
patient should live 
and sleep, summer 
and winter, in a 
well ventilated 
tent or on a ver- 
anda. It is now 
claimed by many 
physicians that 
climate has little 
to do either with 
causing or curing consumption. Still, if the patient 
does not need to consider expense, there is an advan- 
tage in his going to some health resort. A change of 
climate is usually beneficial, and he is likely also to 




Fig. 90. — A Sleeping Veranda Enclosed by 
Awning at a Consumptive's Home. 



284 



PHYSIOLOGY AND HYGIENE 



receive better care than he could have at home. How- 
ever, when cases of tuberculosis are taken in time, the 
patient can generally be cured in his own home, pro- 
vided that he will live out of doors and will follow 
some other special directions. 

Nourishing Food. — After the fresh air comes food. 
The science of curing consumption consists simply in 



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Fig. 91.— The Sun Parlor of a Large Hospital. 

taking in all the oxygen that can be secured, in order 
to purify the blood, thus enabling the tissues of the 
body to get all the nourishment possible out of the 
food. At the same time it is important to take all the 
nourishing food possible. If enough nourishment can 
be taken so that the tissues will be built up faster than 
the disease can break them down, the cure of the pa- 
tient is assured. 

Last of all, but very important to the cure, come 
carefully regulated exercise and rest. 



A WAR FOR THE NATION 285 



HOW TO COMBAT BACTERIA 

Healthy Tissues Resist Disease. — The measures we 
must employ for keeping the bacteria out of our own 
systems, or throwing them off if they do enter, are 
very simple. 

The whole body, let us repeat, should be kept in as 
good condition as possible. Bacteria cannot prey upon 
vigorous and healthy tissue, and if the organs of the 
body they may attack are made up of healthy cells and 
tissue the bacteria soon die and are cast out of the 
body. Thus, with a perfectly healthy body, we shall 
win in the fight without even knowing that we have 
been attacked. 

Importance of Increasing Lung Capacity. — An unde- 
veloped chest lessens the capacity of the lungs. Those 
parts of the lungs that are not used are more liable to 
become the lodging place of the bacillus. So here, 
again, deep breathing and exercises to develop the chest 
and lungs are important. 

Those who have catarrh of the nose or throat should 
wash these parts out with warm salt and water at least 
twice a day. This will keep the membranes clean and 
healthy and prevent the bacteria from finding an open- 
ing for attack there. 

How to Destroy the Bacteria- — The fact that the 
bacteria, when given off by the consumptive, are easily 
destroyed by exposure to sunlight, or heat, makes the 
problem of fighting the disease much simpler than if the 
bacillus usually lived and multiplied outside the body. 



286 PHYSIOLOGY AND HYGIENE 

But the bacillus may live for years in dark, damp 
places, or in undisturbed corners. It is in this way 
that houses in which consumptives have lived become 
infected and are breeding places for the disease, lead- 
ing to the belief that the disease " runs in the family." 
In rooms which have been occupied by a consumptive 
the walls and woodwork should be scraped and scoured, 
repainted and repapered and the floors and every nook 
and cranny that may contain dust or dirt, scrubbed 
with a chloride of lime mixture, made of one part lime 
and twelve parts water. The halls, banisters, and 
other parts of the house should also be cleaned just as 
thoroughly as possible. Then if all the members of 
the consumptive's family will devote themselves to 
building up healthy bodies there will no longer be cause 
to fear the " inherited " disease. 

As the bacteria are carried in the dust, a feather 
duster or a dry broom should never be used in cleaning 
a room occupied by a patient, as they only stir up the 
dust which floats about in the air and settles down 
again. It is better to put damp paper or sawdust on 
the carpet when sweeping, and to use for dusters soft 
or damp cloths, which can be shaken out of doors. 

Children in school should never use a common drink- 
ing cup. The other children may be quite well them- 
selves, but some one in their homes may have this disease 
or some other that is communicable, and in that case 
they could carry the bacteria to others. 



A WAR FOR THE NATION 287 

ALCOHOL AND CONSUMPTION 

The best ptrysicians agree that one of the strongest 
allies the tubercle bacillus has is alcohol. 

In the cure of consumption our great need is, as we 
have seen, to take as much nourishment as possible in 
order to build up the tissues and counteract the power 
of the bacteria. For this we need to have the diges- 
tion in the best possible condition ; and it is important 
also that the lungs, so actively engaged in the purify- 
ing of the blood, should not be hindered in their work. 
Both stomach and lungs are unfavorably affected by 
the use of alcohol; the extent of the injury depending 
in part upon the amount of liquor taken, and in part 
upon the condition of these organs. 

Any appearance of a good effect from taking alcohol 
is deceptive, and if we need further proof of its bad 
effects we find from statistics that there is a larger 
proportion of tuberculosis cases among those who drink 
than among non-drinkers. 

Tobacco, also, is very bad for consumptives, and for 
those predisposed to the disease, as it may weaken the 
heart and thus obstruct the circulation, making it more 
difficult for the lungs to resist attack. 

PRECAUTIONS FOR CONSUMPTIVES 
The following simple directions, taken from a cir- 
cular issued by the Charity Organization Society of 
iSTew York City, should be familiar to everyone, as 
each of us will probably at some time in his life come in 



288 PHYSIOLOGY AKD HYGIENE 

contact with someone who has the disease, and may, 
by knowing these precautions and teaching others how 
to take them, save many lives in this great national 
struggle. 

If we know any one among our relatives or friends 
who has consumption or is threatened with it, we could 
bear our share in the fight by copying these directions 
for them, or better still, by writing to the Charity Or- 
ganization Society, New York City, for copies of their 
circular for distribution where they will do the most 
good. In this way we may help the patients them- 
selves to get well and protect those about them. 

DIRECTIONS 

" Consumption can often be cured if its nature be recognized early 
and if proper means be taken for its treatment. In a majority of 
cases it is not a fatal disease. 

" Consumptives are warned against the many widely advertised 
cures, specifics and special methods of treatment of consumption. No 
cure can be expected from any kind of medicine or method, except the 
regularly accepted treatment, which depends upon pure air, an out-of- 
door life and nourishing food. 

" Consumption is a disease of the lungs, which is taken from oth- 
ers, and is not simply caused by colds, although a cold may make it 
easier to take the disease. It is caused by very minute germs, which 
usually enter the body with the air breathed. The matter which 
consumptives cough or spit up contains these germs in great num- 
bers — frequently millions are discharged in a single day. This mat- 
ter, spit upon the floor, wall or elsewhere, dries and is apt to become 
powdered and float in the air as dust. The dust contains the germs, 
and thus they enter the body with the air breathed. This dust is 
especially likely to be dangerous within doors. The breath of a con- 
sumptive does not contain the germs and will not produce the dis- 



A WAR FOR THE NATION 289 

ease. A well person catches the disease from a consumptive only by 
in some way taking in the matter coughed up by the consumptive. 

"It is not dangerous to live with a consumptive, if the matter 
coughed up by him be promptly destroyed. This matter should not 
be spit upon the floor, carpet, stove, wall or sidewalk, but always, if 
possible, in a cup kept for that purpose. The cup should contain 
water so that the matter will not dry, or better, carbolic acid in a 
five per cent, water solution (six teaspoonfuls in a pint of water). 
This solution kills the germs. The cup should be emptied into the 
water closet at least twice a day, and carefully washed with boiling 
water. 

"Great care should be taken by consumptives to prevent their 
hands, face and clothing from becoming soiled with the matter 
coughed up. If they do become thus soiled, they should be at once 
washed with soap and hot water. Men with consumption should 
weai no beards at all, or only closely cut mustaches. When con- 
sumptives are away from home, the matter coughed up should be 
received in a pocket flask made for this purpose. If cloths must be 
used, they should be immediately burned on returning home. If 
handkerchiefs be used (worthless cloths, which can be at once burned, 
are far better), they should be boiled at least half an hour in 
water by themselves before being washed. When coughing or sneez- 
ing, small particles of spittle containing germs are expelled, so that 
consumptives should always hold a handkerchief or cloth before the 
mouth during these acts ; otherwise, the use of cloths and handker- 
chiefs to receive the matter coughed up should be avoided as much 
as possible, because it readily dries on these, and becomes separated 
and scattered into the air. Hence, when possible, the matter shouldbe 
received into cups or flasks. Paper cups are better than ordinary 
cups, as the former with their contents may be burned after being 
used. A pocket flask of glass, metal, or pasteboard is also a most 
convenient receptacle to spit in when away from home. Cheap and 
convenient forms of flasks and cups may be purchased at many drug 
stores. Patients too weak to use a cup should use moist rags, which 
should at once be burned. If cloths are used they should not be 
carried loose in the pocket, but in a water-proof receptacle (tobacco 



290 PHYSIOLOGY AND HYGIENE 

pouch), which should he frequently boiled. A consumptive should 
never swallow his expectoration. 

"A consumptive should have his own bed, and, if possible, his 
own room. The room should always have an abundance of fresh air 
— the window should be open day and night. The patient's soiled 
wash-clothes and bed linen should be handled as little as possible 
when dry, but should be placed in water until ready for washing. 

" If the matter coughed up be rendered harmless, a consumptive 
may frequently not only do his usual work without giving the dis- 
ease to others, but may also thus improve his own condition and 
increase his chances of getting well." 

FOOD AND EXERCISE 

The first articles of diet for a consumptive person 
should be milk and eggs — as much of each of these as 
he can be prevailed upon to consume. The eggs may 
be beaten up in milk. But the milk and egg diet 
should not take the place of the three regular meals. 
A good deal of meat should be eaten, also vegetables 
and fruit. 

Care should be taken in exercising not to use up the 
strength, but to increase the amount of exercise grad- 
ually. Rest is of greater importance. 

ANIMAL TUBERCULOSIS 

When it was discovered that dairy cows were subject 
to tuberculosis, great fear was felt that human beings 
acquired the disease from the milk and meat of diseased 
cattle. But cases where the disease is carried by the 
milk or meat are rare among adults, although there is 
danger to children feeding on milk. 



CHAPTER XVI 

PUBLIC HYGIENE 

Private and Public Hygiene. — We study physiology 
that we may learn how to live healthy lives; and the 
rules by which we should guide our own lives constitute 
personal hygiene. But there are problems connected 
with the maintenance of health which it is impossible 
for each to regulate for himself. This is because so 
many people live together in towns and cities where 
each one is more or less dependent on others. Our 
scientific men have learned the causes of many diseases 
and have devised methods of preventing them. To 
make these methods effective, the condition of the whole 
community must be considered in any preventive meas- 
ures that are used. For the purpose of safeguard- 
ing the public health various regulations are adopted 
for the whole community. These constitute public 
hygiene. 

BOARDS OF HEALTH AS PUBLIC PROTECTORS 
Hidden Dangers. — If wild beasts were to run in our 
streets, we should feel that we had a right to demand 
that the officers take care of them; but there are in 
our streets sources of disease more dangerous than wild 
animals. We have already learned that some diseases 
are caused by microscopic germs. These germs we can- 
not see. Most people know nothing about them, not 

291 



292 PHYSIOLOGY AND HYGIENE 

even where they are found. If we are to be protected 
against these great dangers, it must be by obeying the 
directions of some who understand how to combat 
them. We have a right to demand protection against 
these unseen dangers as well as against those that are 
seen. 

Boards of Health. — To protect the public from these 
hidden dangers, Boards of Health have been very gen- 
erally established by law. These boards are usually of 
two kinds. One, a State Board of Health, consists of 
a number of men appointed from different parts of the 
State. The duty of this board is to make regulations 
for the whole State and to give advice to the different 
towns and cities on matters relating to public health. 
The other, a city or town Board of Health, consists of 
a number of men, including one or more physicians, 
whose duty it is to see that the proper rules for the 
protection of the public are carried out in the different 
towns and cities. Besides these, there are Water 
Boards whose duty it is to guard the water supply; 
milk inspectors to watch the milk; and food commis- 
sioners and inspectors to see that only proper food is 
offered for sale in the markets. Sometimes there are 
other officers whose duty it is to look after other mat- 
ters of public interest. The good health of the com- 
munity depends primarily upon the proper regulation 
of its food, water, and air, and upon the control of 
contagious diseases. We should always remember that 
the various officers who have these matters in charge 
are working for our good. 



PUBLIC HYGIENE 



293 



INSPECTION OF WATER, VENTILATION, AND FOOD 

Water. — Disease germs are sometimes distributed by 
water. It is necessary for us all to drink water, but if 
our drinking water contains the germs of typhoid fever, 
it is very dangerous. In the country we can guard our 
own well or spring or cistern, but in a town or city we 




Fig. 92. — A Well Properly Located with Reference to the 
Watershed. 



drink the water that is supplied, and perhaps do not 
even know its source. We cannot discover either by 
looking at water or by tasting it whether it is whole- 
some or dangerous. Hence, in well-governed cities 
and towns, it is the duty of the Water Commissioners 
to guard the public water supply for all citizens. Such 
Commissioners try to secure for us a sufficient supply 
of pure water and to guard the supply from pollution. 
The most dangerous material that can get into water 
is sewage, and no water that has sewers emptying into 



294 PHYSIOLOGY AND HYGIENE 

it is fit to drink. Hence a community should if possible 
take its drinking water from some other source than 
rivers, for these are almost sure to receive sewage from 
other cities and towns on their banks. For a similar 




Fig. 93. — An Unhealthful Location for a Well. 

reason, too, the "Water Commissioners frequently fence 
in the reservoirs in order to keep people away from 
them and thus protect them from the dirt and filth 
that would be dangerous to all drinking the water. 

When a community is compelled to get its water sup- 
ply from a river or any other source that is contaminated 



PUBLIC HYGIENE 295 

with sewage, the Commissioners try to devise some 
method of filtering the water that shall remove the 
disease germs, or some method of rendering them harm- 
less. This filtering must be done on a large scale and 
according to scientific methods. We know that the 
small filters that are used in houses are seldom more 
than good strainers. They may separate from the 
water particles of dirt and vegetable matter, but they 
do not exclude the dangerous disease germs. What we 
have learned about the minute size of such germs will 
serve to explain this. 

If the water supply is not properly filtered, the 
Commissioners often advise boiling it in order to de- 
stroy the disease germs. The most important means 
of protecting the water is to prevent all forms of 
excrement and decaying matter from getting into the 
water supply. Money spent in improving the water 
supply yields great returns in increasing the healthf ul- 
ness of the community. 

Fresh Air. — We have already learned how necessary 
it is to our health that we should have an abundance of 
clean, fresh air; but many people do not appreciate 
this, and they and their friends suffer in consequence. 
In rooms made almost air-tight by keeping the windows 
and doors closed, the air becomes foul and is sure to 
be loaded with germs, some of which are likely to be 
dangerous to breathe. In such rooms we breathe over 
and over again the poisonous gases and bacteria, and 
much evil necessarily results. Many people do not 
understand this, and in order to keep warm and to save 



296 PHYSIOLOGY AND HYGIENE 

money, they live and sleep crowded together, several 
in a room, without ventilation. Under these condi- 
tions they " catch" diseases from one another by 
contact and breathing the germs in the impure air. 

Such homes are dangerous not only to the occupants, 
but to all who live in the neighborhood, for the disease 
germs from them are sure to be scattered widely. We 
have a right to demand protection from such dangers, 
and our public officials sometimes find it necessary to 
enter such homes and insist on better conditions. In 
some cases this arouses much opposition to the health 
officers, for the occupants of such homes may feel that 
their rights are being interfered with. But they have 
no more right to breed disease in this way than they 
would have to breed ferocious wild animals and turn 
them loose on the community. 

In the same way, public hygiene demands good ven- 
tilation in school rooms, factories, work-rooms, stores, 
public halls, and in all places where many people live 
together. Plenty of fresh, pure air wherever people 
congregate is an important public safeguard. 

Foods. — Pure foods are no less needed than pure air. 
In trying to get rich quickly, some dealers mix with the 
food they sell cheap materials of little or no food value. 
Water is put into milk, ground beans into coffee. Many 
other foods, such as flours, spices, teas, etc., are fre- 
quently adulterated. It is well to remember that pre- 
pared foods are most likely to be thus adulterated, and 
there is more danger in the cheaper grades than in 
those costing a little more. Cheap canned goods are 



PUBLIC HYGIENE 297 

not really cheap, for we are likely to buy in them a 
considerable proportion of worthless material. 

Sometimes the manufacturers put into food substances 
that are actually harmful. There are kinds of food that 
will not keep well for any length of time, and to preserve 
them certain chemicals are sometimes used. These are 
called preservatives. Those most generally used are 
borax, salicylic acid, and formalin. These are all mild 
poisons, and their constant use in foods is harmful. 
Meats, fish, milk and canned goods are most frequently 
treated with these preservatives. Here again it is the 
cheaper grades that are most likely to be thus ' i pre- 
served ' ' ; the better grades are safer and cheaper in the 
long run. 

It is usually impossible for us to know by examina- 
tion or taste whether our foods are pure or whether 
they are adulterated and ''preserved." This matter, 
therefore, is left to public officials. Pure food laws 
make it a crime to treat food in these ways, and trained 
inspectors can thus protect us from fraud and dangers 
that we should not otherwise know. 

PREVENTION OF CONTAGIOUS DISEASES 
Garbage and Sewage. — Every household produces a 
quantity of refuse material that is both unpleasant and 
dangerous. There is the garbage, or waste from our 
kitchens and our tables. There is also the sewage 
consisting of excrement and other secretions from our 
bodies. The Latter is dangerous, especially if there is 
a sick person in the family. In earlier centuries such 



298 



PHYSIOLOGY AND HYGIENE 



waste was thrown into the streets or gutters, or else 
allowed to soak into the soil until that became saturated 
with filth. When we remember that all this material 
is likely to contain disease germs, we can easily under- 
stand that such disposition of it was not only unsightly 




Fig. 94. — Diagram of House and Street Connections with the 
City Sewers. 

and unpleasant, but dangerous as well. Epidemics used 
to sweep through such cities and people were constantly 
dying from preventable germ diseases. Indeed, in 
many cities people then died faster than children were 
born, and but for the flocking of the country people 
to them, these cities would have disappeared from the 
map. 



PUBLIC HYGIENE 299 

Our modern cities have learned to take care of those 
forms of waste that breed disease. Garbage is required 
to be placed in cans furnished by the householder, and 
the waste from them is regularly removed by garbage 
wagons. Our streets are filled with large underground 
tunnels called sewers, and into these all of the more 
offensive materials from our homes are conducted and 
are washed along in them by water from our sinks and 
closets, and by rain from the gutters. This mass of 
water washes the material out of the city, where it is 
disposed of in some way, and thus the city is kept sweet 
and clean. To make these sewerage systems of real use, 
each house should be properly connected with them. 
Hence the need of careful plumbing. If there are 
leaks in pipes connecting our sinks and closets with the 
sewers, the danger from disease germs is great. A 
careful inspection of plumbing is thus necessary for 
health. 

In many cities people are now prohibited from throw- 
ing papers or any other refuse matter into the streets ; 
they are required to put it into receptacles provided at 
certain places on the streets for the purpose. Most 
cities forbid spitting in the street cars, and some forbid 
it on the sidewalks, for this habit is not only filthy and 
unsightly, but is likely to distribute disease germs. 
The result of these improvements is very noticeable. 
Not only are our cities becoming sweeter, cleaner, and 
more attractive places to live in, but they are also be- 
coming more healthful. 



300 PHYSIOLOGY AND HYGIENE 

PROTECTION FROM CONTAGIOUS DISEASES 

The Spread of Contagious Diseases. — There are some 
diseases, as explained in Chapters XIII and XIV, 
that pass from person to person. When one has such 
a disease the germs that produce them are constantly 
leaving his body. If another person remains near the 
patient the germs may be taken into his body, and 
then he may have the disease. Diseases that may be 
contracted in this way we call contagious. The diseases 
most commonly distributed in this way are smallpox, 
diphtheria, scarlet fever, measles, mumps, and whoop- 
ing-cough. If people mingle freely with each other a 
single case of such a disease is likely to spread and to 
cause an epidemic. Schools may distribute contagious 
diseases not only when the sick children go to school, 
but also when the brothers and sisters of a sick child 
are allowed to attend school, for they may carry the 
disease germs in their clothes. 

To prevent the distribution of contagious diseases is 
one of the most important duties of the health officers. 
Yarious rules for isolation have been devised. Isola- 
tion means simply keeping the patient away from those 
who are liable to take the disease from him. A child 
who has a contagious disease should never be allowed 
to attend school, and should always be kept in a 
room by himself, away from all members of the family 
except the one who nurses him. In the more severe 
contagious diseases, such as smallpox, scarlet fever and 
diphtheria, where the chances of contagion are great, 
the patient is frequently taken to a special hospital 



PUBLIC HYGIENE 301 

where lie can be more carefully attended and where 
there is no chance of his spreading the disease. He is 
thus kept away from others until he has so completely 
recovered that he can no longer give the disease, the 
length of time being determined by physicians. 

Treatment of Infected Objects. — Anything that comes 
in contact with a patient may become infected with the 
germs of disease, and unless properly cared for, may be 
the means of spreading the infection. This applies to 
excretions from his body, and also to clothing, bedding, 
towels, handkerchiefs, knives, forks, drinking cups, 
books, toys, food left by the patient, etc. Before such 
objects should be handled by others, the germs upon 
them must be destroyed, or, as we say, the article must 
be disinfected. All articles of little value, like bits of 
cloth, toys, and food, should be destroyed. Others 
may be made safe in several ways. 

It is most important to understand fully that simple 
boiling is quite sufficient to destroy any dangerous 
germs that are likely to be left on clothing, towels, 
bedding, handkerchiefs, eating utensils, etc. While 
some bacteria produce spores that are not killed by 
simple boiling, none of the germs of the common 
diseases do so. Any infected article, therefore, that 
can be placed in a boiler with water and boiled for 
fifteen minutes to half an hour, will be rendered per- 
fectly safe, since this kills all common disease germs. 
Steam will do the same, if it can be applied to objects 
in closed vessels and so, too, will the dry heat of an oven. 

Objects which cannot be boiled may sometimes be 



302 PHYSIOLOGY AND HYGIENE 



soaked or washed in a disinfectant. These disinfect- 
ants are solutions which contain chemicals that kill 
germs quickly. They are all poisonous, should always 
be labeled POISON, handled with care, and never taken 
into the mouth. The best of them are the following : 

Formalin. — Formalin is a liquid which looks like 
water, but is a powerful disinfectant. Any article 
soaked in a 2% to 4% solution will be thoroughly 
disinfected, and is no more injured by the formalin 
than it would be by soaking in water. If formalin 
stands in the open air, it gives off a gas very irritating 
to the eyes. This gas is the real disinfecting agent, 
and health officers frequently use it to disinfect a room 
after it has been occupied by a patient with a conta- 
gious disease (as explained on page 304). 

Corrosive Sublimate. — Corrosive sublimate is in- 
tensely poisonous. One part of it dissolved in one 
thousand parts of water forms a powerful disinfectant. 
It may be bought in tablets, eight of which dissolved 
in a gallon of water give the desired strength. It 
may be used for washing floors, furniture, or walls of 
rooms, or for disinfecting excreta which should be 
allowed to soak in the disinfectant an hour. It must 
not be used on metals, since it injures them. In 
strength of 1 part corrosive sublimate to 2000-4000 
parts water, it may be used to disinfect wounds. 

Chloride of Lime. — Chloride of lime, or bleaching 
powder, is a cheap and very good disinfectant. One 
pound dissolved in eight gallons of water gives the 
desired strength. It can be used just like corrosive 



PUBLIC HYGIENE 303 

sublimate and allowed to act an hour or more. It is 
not so violently poisonous as corrosive sublimate, and 
does not injure metals. 

Carbolic Acid. — Carbolic acid is one of the best and 
most widely used disinfectants. It must not be used full 
strength, one part of the acid in twenty of water being 
the right proportion for most purposes. It is rather 
costly, and for ordinary disinfection of rooms or excreta 
is not so good as the cheaper disinfectants. The fact 
that it has a strong odor does not make it of any more 
value as a disinfectant. A 2 % to 5 % solution can be 
used upon the flesh to disinfect wounds. 

In the use of any disinfectant it should be remem- 
bered that the object must be actually wet with the 
disinfectant. Pouring a little on the floor of a room, 
or allowing it to stand in an open vessel, is of no value 
whatsoever, even though, like carbolic acid, it has a strong 
odor. The odor has no power of destroying the germs. 

Care of the Sick Room. — The health officers also per- 
form a very important service in caring for the room in 
which a patient has been ill with some contagious 
disease. After the recovery of the patient, the bacteria 
that cause the disease are generally still present in the 
room ; indeed, some of these germs live for many 
months in dark corners or in clothing if no attempt is 
made to destroy them. Hence it is very important that 
a room and its furnishings, which may probably con- 
tain large numbers of such dangerous germs, should 
be thoroughly cleansed and all the bacteria there de- 
stroyed before it is used again. This the health officers 



304 PHYSIOLOGY AND HYGIENE 

undertake to do; the process is called fumigation or 
disinfection. 

A common method is first to make the room as near 
air-tight as possible by stuffing all the cracks with 
cotton, or better, pasting strips of paper over all places 
where air may enter ; then a large quantity of some 
germ-destroyer is burned in the room, which is left 
closed for twenty-four hours. 

Hospitals. — As an aid in the treatment of disease, 
our modern cities have built hospitals. Here the best 
of care and medical attendance is given to the sick. So 
carefully are the hospitals managed that the patient has 
usually much greater chance of speedy recovery there 
than if he remains at home. Patients are cared for at 
small expense, and frequently no charge is made to 
those who cannot afford to pay. 

QUESTIONS 

1. What do we mean by personal hygiene? 

2. What do we mean by public hygiene ? 

3. Why do cities have Boards of Health ? 

4. Name some officials who care for the health of the public? 

5. How may the drinking water become impure ? 

6. Explain the importance of fresh air. 

7. Why do we have food inspectors? 

8. How should garbage and sewage be disposed of ? 

9. How can we avoid taking or spreading contagious diseases ? 

10. Name four good disinfectants. 

11. How may the bacteria in a sick room be destroyed? 



CHAPTER XVII 
WHAT TO DO IN EMERGENCIES 

There are many times when a knowledge of what 
to do in case of accident may be of great advantage 
and occasionally such knowledge may be the means of 
saving life. 

Some important emergencies have already been men- 
tioned on various pages of this book : 

Broken bones. — See page 132. 

Burns. — See page 177. 

Dislocations. — See page 140. 

Browning. — See page 120. 

Foreign bodies in the eye. — See page 221. 

Freezing. — See page 178. 

Sprains. — See page 140. 

TOOTHACHE 

Toothache is always a warning that the teeth need 
attention. In many cases a cavity will be found in the 
aching tooth, and in this case the pain may be stopped 
for a time by twisting up a bit of cotton, dipping it 
in oil of cloves and inserting it into the cavity. All 
cavities in the teeth should be filled, for they serve as 
lodging places for troublesome bacteria. 

305 



306 PHYSIOLOGY AND HYGIENE 

NOSEBLEED 

Nosebleed is usually not serious and will soon stop 
of itself. The head should be held erect and not bent 
over a basin. The pinching of the nostrils will some- 
times hasten the clotting of the blood so as to stop 
the bleeding. If it continues persistently, ice (wrapped 
in a towel for convenience), applied to the back of 
the neck and the bridge of the nose, will frequently 
check it. Sometimes it may be necessary to put a 
plug of cotton in the nose. While the bleeding con- 
tinues, and for some time afterwards, one should not 
blow the nose nor cough if avoidable, since it is likely 
to start the bleeding afresh, by breaking away the 
clots that are closing the broken blood vessels. 

CHOKING 

A solid object passing through the throat may become 
lodged in one of the smaller passages below, producing 
choking. If something gets into the windpipe so as 
to prevent the passage of air into the lungs, a violent 
fit of coughing starts at once and the irritating object 
will be blown out with the blast of air, unless it is too 
firmly lodged. Unless it is quickly removed, however, 
the person will die. 

Large objects do not often get stuck in the windpipe. 
It is more common for them to get lodged in the gullet, 
where they are less immediately dangerous, since they 
do not prevent breathing. They must be removed, 
however, and the best thing to do is to have the person 



WHAT TO DO IN EMERGENCIES 307 

bend his body forward over a chair and then to slap 
him on the back between the shoulders. The danger 
in choking is so great that one should never allow 
himself to carry in his mouth small objects, like buttons, 
pins, tacks, beads, marbles, etc. This is a particularly 
dangerous thing to do when one is running. 

CRAMPS 

Cramps is the name given to a violent contraction of 
the muscles, usually of the legs or arms, that renders 
them stiff, so that for the while one cannot move them. 
The trouble is most likely to occur when one has been 
for some time in cold water, and hence frequently 
attacks swimmers. If it occurs when one is in deep 
water and no help is at hand, even a good swimmer is 
likely to drown, since he cannot move his muscles and 
becomes helpless and faint from pain. It is not safe 
therefore to swim into deep water unless some one is 
near by who can aid if the swimmer is seized with 
cramps. The longer one is in the water the more 
likely is he to have cramps. The trouble comes on 
very quickly and does not last long, though the muscles 
may be sore for a day or two. Although most common 
when one is swimming, one may have cramps at any 
time. Nothing needs to be done, for the trouble soon 
disappears. 

STINGS OF INSECTS 

An insect such as a bee^ hornet, wasp or yellow 
jacket wounds by thrusting into the skin a sharp, 
needle-like sting which carries with it a very irritating 



308 



PHYSIOLOGY AND HYGIENE 



Fig. 95. 




Bumble Bee. 



poison. In the case of most insects the sting is smooth 

and can be at once withdrawn so that the animal can 

sting again. The sting of the 
honeybee is barbed and cannot 
be removed from the wound, 
but is pulled out of the body of 
the bee when it flies away. 

The sting may then be seen still in the wound and 

should be removed by forceps or the point of a knife. 

The pain is produced by 

the poison, and since this 

is an acid poison an alka- 

lineremedyisbest. Soda 

or ammonia applied to 

the spot is good, but 

nothing is really better 

than wet mud, which will soon relieve the pain. If 

insects are let alone they will not sting. When they 

light on flowers one is hold- 
ing, or upon some sweet 
food, if allowed quietly to 
feed upon it, they will soon 
fly away without stinging. 

If one grows excited and tries to strike, then they will 

get angry and sting. 




Fig. 96. — A Wasp. 




Fig. 97. — A Honeybee. 



SNAKE BITES 

Many people have a great fear of snake bites. While 
it is true that some snakes have a poisonous bite, this 
danger is one of the rarest, a far lesser danger than 



WHAT TO DO IN EMERGENCIES 309 

playing with matches or teasing dogs. Poisonous 
snakes are not common in this country and not found 
at all in settled localities. Aside from a rare species 
found in Mexico, there are only three kinds here that 
are really poisonous : the rattlesnake, the water moc- 
casin, and the copperhead. All others are harmless, in 
spite of various stories to the contrary. 

In biting, the harmful snake forces a very violent 
poison into the flesh, which is soon carried over the body 
through the circulation. The first thing to do is to tie a 
handkerchief around the limb that is bitten, above the 
bite, and then insert a stick inside the handkerchief, 
twisting the stick so as to compress the blood vessels and 
stop the flow of blood. This will prevent the poison 
from flowing with the blood over the body. The wound 
should then be sucked to remove as much of the poison 
as possible. The poison does no injury in the mouth and 
no harm to the person who sucks it, if care is taken to 
empty the mouth at once. If the wound does not bleed, 
it should be cut open to induce bleeding. It is necessary 
to proceed quickly, since every moment is precious. 

POISONING FROM IVY AND POISON DOGWOOD 

Poison ivy and sumac produce an oily secretion that 
is poisonous to most people if it gets on the skin. 
Poison ivy is a common vine, growing over rocks and 
stone walls or climbing up trees. Its leaf is waxy in 
the spring, glossy green in the summer, and scarlet in 
the fall. It resembles somewhat the harmless and beau- 
tiful woodbine, or Virginia creeper, but may be easily 



310 



PHYSIOLOGY AND HYGIENE 



distinguished by the fact that it has three leaflets, while 
the woodbine has five. It has yellowish green berries, 
while the woodbine has dark blue berries. 

The poison dogwood, or sumac, is a shrub growing 
chiefly in swamps. It has leaves each with eleven to 
thirty-one leaflets and produces loose clusters of white 

berries. The beautiful 
flowering dogwood 
should not be confused 
with it. This grows on 
dry ground, has leaves 
of seven to thirteen 
leaflets and dark red 
fruit, and is perfectly 
harmless. The poison 
of the dogwood is more 
severe than that of the 
ivy. 
Eig. 98. — The Leaves of the Wood- When one has been 

bine and the Poison Ivy. once poisoned he is 

more likely to be poisoned a second time. The poison 
is of an oily nature and may be removed by thorough 
washing with soap and water. If one acquires the habit 
of thoroughly washing the hands, arms, face, and neck 
with warm soap and water immediately after coming from 
a tramp in the woods or fields, he will usually be able to 
avoid the poisoning from these plants, since it takes 
several hours or sometimes a day or two before the poison 
can do any injury. The poisoning shows itself by an 
intense itching, swelling, and blistering of the skin, and 




WHAT TO DO IN EMERGENCIES 311 

is sometimes very disagreeable. It wears off in a few 
days, and in the meantime there is no better remedy 
than plain soap and water. 

ACCIDENTS FROM ELECTRICITY 

Electricity is a useful friend, but may be dangerous 
if one is not careful. A large wire used for light- 
ing purposes or for running trolley cars may contain a 
current of a power high enough to kill any one who 
allows it to pass through his body. A wire with a 
current in it is called a " live wire," and is dangerous 
to handle ; indeed, if the current is a powerful one, 
even touching the wire would mean instant death. 

One should never touch a loose wire attached to an 
electric circuit, and unless one has definite knowledge 
to the contrary all wires attached to electric poles should 
be considered dangerous to touch. Sometimes a live 
wire is seen lying with its loose end in the street or on 
the sidewalk, and some one thoughtlessly trying to kick 
it aside gets a fatal shock. Electricity will not pass 
through rubber, dry silk, or dry paper, and if one picks 
up the wire with rubber gloves, a rubber overshoe, or 
a thick mass of newspapers the electricity will not touch 
him. If these objects are wet, however, they will let 
the electricity pass and give the shock to the person 
trying to pick up the wire. If one picks up the end 
of a wet rope or kite string lying on a live wire, it may 
convey the electricity to him. 

If a person gets tangled up in a wire with a current 
not strong enough to kill him at once, it may burn him 



312 PHYSIOLOGY AND HYGIENE 

badly. He is unable to free himself, for the electricity 
makes it impossible for him to use his muscles. An- 
other person must loose him, handling the wire with 
rubber or absolutely dry material. Burns made by 
electricity are slower in healing, but they should be 
treated like other burns. 

SUNSTROKE AND HEAT PROSTRATION 

Although sunstroke and heat prostration are both 
due to excessive heat, they are different, and have to be 
treated differently. Sunstroke is due to the direct rays 
of the sun shining upon one's head on excessively hot 
days. It is to be avoided by protecting the head from 
the sun by an umbrella or a broad hat, or by keeping in 
the shade. A person who has sunstroke becomes dizzy, 
and perhaps unconscious, and his skin will be found to 
be hot and dry. He should be removed to the nearest 
shade and placed in a sitting posture against a tree or 
some other support. His clothing should be loosened, 
cold water poured over his head, or his body rubbed 
with bits of ice. If he can swallow, he should be given 
cool drinks, but never alcoholic stimulants. 

Heat prostration may be caused by excessive heat 
away from the direct rays of the sun, as in a hot engine 
room, for example. The person will be pale and faint, 
but his skin will not be hot and feverish. He should 
be removed to the nearest cool spot, placed flat on his 
back, his clothing loosened, and his hands and feet 
rubbed to restore circulation. The face and body 
should be bathed in warm water, and warm cloths 



WHAT TO DO IX EMERGENCIES 313 

should be applied to bis bod}-. Warm drinks may be 
given. 

In all cases a physician should be summoned as soon 
as possible. A person who has once been prostrated 
by heat is more subject to a second attack, and needs 
afterwards to be particularly careful not to expose him- 
self to heat. 

POISONS 

The treatment to be followed when one swallows 
poison varies with the kind of poison. There are a 
few general rules always applicable. 1. Act promptly, 
for the delay of even a few minutes may make the dif- 
ference between recovery and death. 2. Send for a 
physician immediately. 3. Until the physician comes, 
cause the patient to vomit. 4. Administer an antidote 
to the poison. 

Induce immediate vomiting, so as to remove as much 
as possible of the poison from the stomach. This may 
be done by giving a teaspoonful of powdered mustard 
in a glass of warm water. After the mustard has been 
swallowed, tickle the back part of the throat with the 
finger or a feather. If vomiting does not occur at once, 
repeat the dose in about ten minutes. Common salt 
will sometimes serve in the place of mustard if the 
latter is not at hand. 

Administer some antidote to counteract the effect of 
the poison which remains in the body. The antidote 
to be used depends upon the poison. The most com- 
mon poisons and their antidotes are given below. In 



314 PHYSIOLOGY AND HYGIENE 

their treatment vomiting should be induced, unless 
otherwise stated. 

Acid poisons, like sulphuric acid (oil of vitrol), nitric 
acid (aqua fortis), muriatic acid, oxalic acid, carbolic 
acid, etc. In these cases the vomiting should be omitted, 
and three or four spoonfuls of soda or of baking 
powder should be given to neutralize the acid. The 
whites of three or four eggs, lime water, or even soap- 
suds may also be used. Oxalic acid and carbolic acid, 
even when neutralized, remain poisonous. The services 
of a physician are needed to wash out the stomach. 

Alkali poisons like ammonia, potash, or lye should be 
created with an acid to neutralize the alkali. Vinegar 
and water, or lemon juice, giving all the person can 
drink, constitutes the antidote. 

Arsenic is an ingredient of paris green, many fly 
powders, and green paints. Mix some tincture of iron 
with baking powder and give the patient a spoonful 
of the brownish powder which appears, or use the white 
of eggs. Administer every minute or two. 

Lead is found in sugar of lead, white lead used by 
painters, tinfoil of tobacco coverings, etc. Administer 
a strong solution of Epsom salts or Glauber's salts. 

Mercury is found in corrosive sublimate, used for 
various purposes, chiefly as a disinfectant. Omit try- 
ing to induce vomiting and administer the white of 
an egg, or flour beaten up with milk or water. 

Opium is found in laudanum, paregoric, soothing sirups, 
cholera mixtures, etc. Give strong coffee or aromatic 
spirits of ammonia (fifteen drops of the ammonia every 



WHAT TO DO IX EMERGENCIES 315 

few minutes). Use all means to keep the patient mov- 
ing and to prevent his sleeping. 

Strychnine. — Use chloroform or ether to relieve the 
violent spasms. Aromatic spirits of ammonia or bro- 
mide of sodium may be used, five grains of the latter 
every half hour. Artificial respiration may be neces- 
sary. 

Phosphorus. — Children sometimes suck the heads off 
matches. Common matches contain phosphorus, which 
is a poison. The treatment for phosphorus before the 
doctor comes is to induce vomiting and then to give 
the patient the white of an egg followed by Epsom 
salts. 

The after-treatment for poisoning must be such as to 
combat dangerous symptoms which have arisen. This, 
however, must be left to a physician, and cannot be 
done without special knowledge of medicine. 

QUESTIONS 

1. "Why should you keep the cavities in your teeth well filled ? 

2. How may a nosebleed be checked ? 

3. What should you do if some one is choking from having 
some object lodged in his throat? 

4. How should the sting of a bee be treated? 

5. How may you prevent ivy poisoning ? 

6. How may a "live " electric wire be handled? 

7. How should you treat a case of heat prostration ? Of sun- 
stroke? How tell the difference between them ? 

8. What is the first thing to do when one has swallowed poison ? 



CHAPTER XVIII 
HOW TO DEVELOP OUR BODIES 

Introductory. — While we are learning about the 
different parts of the body we should not forget that 
the object of all this study is to learn how to care for 
the body as a whole, and we should consider what we 
may do to keep it at its best, working easily and to 
advantage. In the chapters on " Respiration, " "The 
Muscles," and "The Blood" there are references 
to exercise, to breathing, and to the uniform develop- 
ment of all the muscles; let us in this chapter look 
especially into the practical side of the matter. 

It is easy to learn what we should do, but unless we 
take the time and trouble to practice what we learn, 
regularly and thoroughly, we cannot expect to get 
much benefit. 

We must remember, too, that the most wonderful 
of those bodily changes and actions that take place 
day after day do not happen on the surface of the body, 
where we might see and feel them. Because this is true 
we are inclined to think that breaking the laws of health 
is harmless if we feel no ill effects from such mistakes. 
That, however, is as foolish as it would be for us to think 
that the sun stopped shining on a cloudy day just be- 
cause we were unable to see it. We cannot make our 

316 



HOW TO DEVELOP OUR BODIES 317 

feelings a test of the physical effects of our actions; nor 
can we expect to see or to feel any extraordinary ben- 
efit when we begin to follow carefully the rules of health 
which we have been taught, or to take systematic exer- 
cise, as will be suggested in this chapter. Still we may 
be sure that in these ways we shall certainly be adding 
to our strength and to the power of our bodies; and in 
time the effects will be evident. 

Importance of Developing the Body. — The muscular 
system is developed by work and by exercise ; both are 
necessary to our health and therefore to our usefulness 
and happiness. Our bodies are the means by which we 
accomplish all that we have to do in this world, and 
unless they are strong and each organ does its part 
well, we cannot expect to accomplish what we wish. 
G-ood work is impossible without good bodies. 

Necessity of Work and Exercise. — Why is it that peo- 
ple after they are grown frequently lose the good health 
that they had when they were children? Usually they 
give some parts of their bodies plenty of work to do, 
but they do not give the whole body systematic exer- 
cise and healthful recreation. 

Perhaps as boys and girls they were not taught a few 
simple facts which everyone should know with regard 
to the care of the body and how to exercise it in order 
to strengthen and develop all its parts. It is true that 
most boys and girls get a great deal of out-of-door ex- 
ercise in their sports and games, and thus keep some of 
the muscles strong and well ; but something more than 
this is needed. 



318 PHYSIOLOGY AND HYGIENE 

Dangers of Unequal Development. — Perfect health re- 
quires that all the muscles be developed uniformly, but 
our games and sports, as a rule, influence only certain 
sets of muscles, often at the expense of others. Even 
athletes may have consumption or heart trouble, be- 
cause in training particularly the muscles they wish to 
use, they neglect the training that is necessary to de- 
velop equally the strength of the lungs — not the chest 
muscles only — and the heart; two most important 
organs of the body, upon which the proper working 
of all the others depends. 

In addition to our games, we need, therefore, to 
practice exercises by which each part of the body shall 
receive a reasonable share of attention and be developed 
in proportion to its usefulness and needs. 

Relation of Oxygen to Muscular Effort. — When we 
exercise a muscle vigorously it requires more nourish- 
ment, and for this oxygen is the first essential (page 
116). As we must secure the oxygen by drawing the 
air into the lungs, exercises which will help us to breathe 
more deeply and thus take more oxygen into the sys- 
tem should receive most careful consideration. 

BREATHING 
Deep Breathing. — To breathe deeply, then, is the first 
rule to be observed in healthful exercise. We must 
first understand the importance of breathing through 
the nose (page 105). Even in violent exercise there are 
seldom conditions that properly admit of mouth breath- 
ing. The fact that certain forms of vigorous exercise 



HOW TO DEVELOP OUR BODIES 319 

compel us to fill and empty the lungs frequently, shows 
us one of the reasons why they are beneficial. 

Significance of Yawning and Stretching. — Nature tries 
to meet this necessity for oxygen in many ways; one 
of them is by giving us the desire to yawn and stretch 
when we are tired or have been sitting still for a long 
time. People frequently discourage this habit in chil- 
dren because it " looks lazy", but when we consider 
that it relieves the muscles and organs of the body from 
a cramped or strained position, and at the same time 
fills the lungs with a fresh supply of oxygen, we can 
see that this is really a valuable exercise, though one 
that cannot be taken at all times and in all places. 
When we feel like stretching, it is well to take some 
light form of exercise to relieve the strain and fatigue 
against which the body is protesting. 

Since, however, it is necessary in performing these 
exercises that our bodies be in a correct position, it is 
very important that we should first learn to know when 
the body is in proper poise. 

Sitting. — Yery few of us know how to sit or stand 
properly, and yet the correct position of the body is 
the basis for all our physical development. 

"We think it is more comfortable and restful to lounge 
down in our seats or lean upon our desks at school, or 
to sit in rocking chairs at home, but as a matter of fact 
such positions are in the end weakening and tiresome. 
Why? Because in these positions the chest is con- 
tracted so that it is impossible to get the proper amount 
of air into the lungs, and the organs of the abdomen are 



320 PHYSIOLOGY AND HYGIENE 

pressed together or out of position, so that they cannot 
work freely. All these things cause a strain on the 
booty which does not exist if we sit erect, with the body 
comfortably poised, and give each organ plenty of space 
and nourishment. 

So, if you would keep your strength and secure the 
proper development of your bodies, learn first of all to 
sit erect. 

Standing. — If we do not stand erect the organs of the 
trunk — the lungs, heart, stomach, etc. — have not suffi- 
cient room, and so cannot perform their functions prop- 
erly, causing unnecessary fatigue and sometimes actual 
discomfort. 

Then, too, we must consider the force of gravitation, 
which is continually drawing objects toward the earth. 
If we stand erect, our bodies are well balanced; that 
is, the force is distributed evenly; while if we stoop 
forward there is a strain that we constantly resist, wiaich 
causes us to grow tired sooner than otherwise. 

Poise. — For a graceful, well-balanced poise, we should 
stand with the legs straight, head erect, chin drawn 
slightly in, and chest high, and with the weight chiefly 
on the balls of the feet. Too frequently we stand with 
the weight on the heels, the hips coming forward and 
the abdomen thrust forward. Watch some day the 
people you meet, and see what proportion of them stand 
in this way. Compare the ease and grace of those 
who stand with the body properly poised. Faulty 
poise is not to be corrected by drawing the abdomen in 
and holding it back tensely. This is not necessary if 



HOW TO DEVELOP OUR BODIES 321 

the proper balance of the body is secured as indicated 
above. Further, it is an unwise way of correcting the 
fault, as the muscles of the abdomen should be left free 
to expand and contract naturally; and this may be 
accomplished without allowing the abdomen to be 
thrust forward. 

The chest should not be thrown too far forward ; this, 
however, is not a common fault in position. A good 
rule to follow is to stand in such a way that the lips, 
chin, outer line of the chest, and the tips of the toes 
are in a straight line. A long pole or fishing rod held 
vertically against the front of the body may be used to 
test the position. 

The balance of the body may be tested by a simple 
little exercise. Stand squarely on both feet in the posi- 
tion that is most natural to you. Then carry the weight 
forward to the toes; carry it back to the heels, and 
finally to the balls of the feet; resting there. Compare 
this position with the natural one you first assumed. 
You will probably discover that you are accustomed to 
stand with the weight too near the heels. 

BREATHING EXERCISES 
The Process of Breathing. — Before we think of special 
breathing exercises for the development of the body, 
let us see what is said in Chapter Y about the proc- 
ess of breathing or respiration. We read how air 
is. drawn into the lungs largely through the action 
of the muscular wall called the diaphragm, which by 
moving downward increases the size of the chest cavity, 



322 PHYSIOLOGY AND HYGIENE 

thus causing the air to enter the lungs to fill the en- 
larged space. Its upward motion by decreasing the same 
cavity, causes the air to leave the lungs, as there is not 
then room for so much air. "While all this happens 
easily and regularly, we are probably hardly conscious 
even of the fact that we are breathing; we usually have 
no sensation from the motion of the diaphragm, and 
the upward and outward movement of the ribs during 
respiration is likewise unnoticed. 

Necessity of Deep Breathing. — The important point 
is that the lungs should be well filled with fresh air, 
and this frequently. In ordinary breathing we expand 
the top of the lungs, while the lower part of them may 
be inactive, not doing its proper duty toward purifying 
the blood and enriching it with oxygen. So our prob- 
lem is to set all portions of our lungs to work. If you 
find that your abdomen does not move in and out 
noticeably as you breathe, call a halt and see whether 
you are not letting the upper part of your lungs do 
work that ought to be done by the lower lungs, aided 
by the ribs and the diaphragm'. 

In the beginning we may have to think about it every 
time we take a long breath, and perhaps shall forget the 
deep breathing unless we are reminded; but if we per- 
sist, we can finally form the habit, and when this is 
done, it will be sure proof that we have greatly in- 
creased our strength and our power of endurance. 

The following exercises are recommended by several 
well-known experts in physical training, prominent 
among whom is Dr. Claes J. Enebuske, from whose 



HOW TO DEVELOP OUR BODIES 



323 



" Progressive Gymnastic Day's Orders " ' many valu- 
able suggestions have been drawn. They are so sim- 
ple that they may be taken at home without any super- 
vision; the pupil who practices them regu- 
larly, night and morning, will certainly find 
a gain in his strength and in muscle control. 
Exercise i. — Stand erect, heels together, 
toes out, hands down at side. Draw a deep 
breath slowly, and at the same time raise the 
arms slowly from the sides until the palms 
nearly meet over the head, as shown in Fig- 
ure 99. Lower the arms gradually, exhaling 
slowly. Repeat each of these exercises about 
eight times. 

Exercise 2. — Stretch the 
arms straight out in front 
of the body, palms facing. 
Keeping the arms in a hor- 
izontal position (see Fig. 
100), move them slowly backward, 
and see how near you can come to 
bringing the hands together at the 
back, without bending or lowering 
the arms. Inhale and exhale as 
before. 

Exercise 3. — Arms straight out in 
front, palms down. Raise the arms 
slowly over the head, then as far back as possible, 

1 The illustrations used in this chapter are taken from the same 
book. Published by Silver, Burdett & Company. 



Fig. 99. 




Fig. 100. 



324 PHYSIOLOGY AND HYGIENE 

down, and to original position, making in this way a 
sort of crooked circle in the air with the hands. In- 
hale slowly as the arms are raised, and exhale as they 
are lowered. 

To vary these exercises from time to time, instead of 
exhaling as the arms descend, hold the breath until 
the arms are in their original position. Then exhale 
very slowly. 

WALKING 

Having learned to stand correctly, and to breathe 
deeply, we must next learn how to walk in such a way 
as to make the best possible use of our muscles, and 
gain strength and endurance. 

Probably a majority of people rest their weight as 
they step more on the heel than on the forward part 
of the foot. This is not right. As each foot touches 
the ground the weight should be thrown upon the ball 
of the foot, and as it leaves the ground pressure should 
be exerted upon the same part and upon the toes. This 
will carry the body forward easily, and the movement 
when once acquired will enable one to walk much more 
rapidly and with less fatigue. It also develops the 
muscles of the foot and ankle, and of the lower part of 
the leg. 

The Indians, and athletes who are trained for walk- 
ing long distances, use this method. At first it should 
be practiced for only a few minutes at a time, as one is 
using muscles that are not accustomed to the work, 
and so tire quickly. But when one comes to realize the 



HOW TO DEVELOP OUR BODIES 



325 



delightful ease of motion which is secured in this way, 
he will think the lesson was well worth while. 

Deep breathing as we walk adds very much to our 
feeling of buoyancy and ease in motion. 

When we have learned to sit, stand, and walk cor- 
rectly, we shall have formed the valuable and necessary 
foundation for the correct performance of all other phy- 
sical exercises. 



EXERCISES FOR SUPPLENESS— EASE OF MOTION 

Power of endurance and skill in the use of the body 
depend very largely upon ease of motion. We usually 
think of farmers and other out-of-door laborers as types 
of strong men. But frequently we 
notice that they are awkward and stiff 
in their movements, and clumsy in 
the use of their hands; any exercise 
to which they are not accustomed soon 
tires them. This is because their work 
compels them to use only certain sets 
of muscles. The muscles which are 
not used get stiff and do not respond 
readily when the brain orders them 
to move. 

So, to acquire ease of motion, we 

must practice exercises to keep all the 

muscles flexible. 

Exercise 4— Stand erect, hands on hips (see Fig. 101). 

Keeping the legs straight, bend forward from the 

waist until the upper part of the body is parallel 




326 



PHYSIOLOGY AND HYGIENE 




Fig. 102. 



with, the floor, then back as far as 
possible. Return slowly to an erect 
position. 

Exercise 5. — Same position. Bend 
the body from the waist, first to one 
side then to the other, as shown in 
Figure 102. 

Exercise 6. — Stand as before, rise on 
tiptoe, then bend the knees, letting the 
body sink quickly, then up, still on 
tiptoe, and back to position again. 
The body and head must be kept erect 
in this exercise. These exercises are 
also valuable in strengthening the muscles of the 
abdomen and waist. 

Dancing is excellent for giving flexibility 
and grace. 



DEVELOPMENT EXERCISES 
FOR THE ARMS 

Exercise 7. — Stand with 
hands on shoulders, as in 
Figure 103. Thrust arms 
quickly out sideways and 
back to position, then 
straight up and back. Re- 
peat four times. 

Exercise 8. — Arms out 
at sides, palms up. Bend elbows 
shown in Figure 104. Thrust 




Fig. 103. 



as 




one 



Fig. 104. 



HOW TO DEVELOP OUR BODIES 327 

arm out to full length, at the same time bending the 
other so that the hand strikes the shoulder. Repeat, 
the arms bending and straightening alternately. 

These arm movements may be varied by using light 
dumb-bells or other objects of about the same weight. 
As the strength increases the weight may be increased. 

Exercises on the bars and rings are especially good 
for the development of the arms, and any boy who can- 
not go to a gymnasium can rig up a single bar or pair 
of rings at his own home. 

Bar or Ring Exercise. — Grasp the bar or rings firmly, 
letting the body hang perfectly straight, feet together. 
Draw the body up by the hands until the chin is on a 
level with the hands. As the muscles grow stronger 
it will be possible to bring the breast on a level with 
the hands. 

FOR THE SHOULDERS, BACK AND CHEST 
Exercis3 g. — Arms hanging loosely at the sides. Raise 
the right shoulder, throw it forward, down, back, up, 
thus describing a circle. Repeat with the other 
shoulder. Then circle in the opposite direction. 

Exercise 10. — Arms straight out at sides, palms front. 
Swing the whole arm from the shoulder, each hand thus 
describing a circle in the air. 

Exercise 11. — Arms over right shoulder as if holding 
a bat. Left foot forward. Fling arms and body for- 
ward and down as if striking very hard at something 
on the ground. Repeat with arms over left shoulder, 
right foot forward. 



328 PHYSIOLOGY AND HYGIENE 



FOR THE NECK 

Exercise 12. — Body erect. Bend head forward and 
back several times, then to the right and left. 

Exercise 13. — Roll the head around, circling first to 
the right, then to the left. 

FOR THE HANDS AND WRISTS 

Exercise 14. — Arms straight out at sides, palms down. 
Bend the wrists, throwing hands as far back as possible, 
then down. Repeat several times. 

Exercise 15. — Keeping wrist and back of hand level, 
fingers straight, bend fingers down from the knuckles, 
then back as far as they will go. 

Exercise 16. — Relax the muscles of hands and fingers, 
and letting the hands droop from the wrists, shake them 
until they are thoroughly relaxed; as the hands are con- 
tinually employed in grasping things, the muscles are 
generally contracted, and they should be frequently 
relaxed. 

FOR WAIST AND ABDOMINAL MUSCLES 

All exercises that involve bending from the waist are 
good. We have found several of these in the section 
on suppleness. 

Exercise 17. — Stand with feet slightly apart. Roll 
the body from the waist, describing a circle in the air 
with the head. Circle in the opposite direction. 

Exercise 18 — Stand with feet apart, arms straight 



HOW TO DEVELOP OUR BODIES 



329 




Fig. 105. 



above the head. Bend forward from the waist until 
the body takes almost the position of an inverted V, 
as in Figure 105. 

Exercise 19 — Stand with hands 
on hips. Take a long step forward, 
bearing the weight on the forward 
foot (see Fig. 106). Back to posi- 
tion. Kepeat with the other foot 
forward. 

$/ JJ I FOR THE LEGS 

Exercise 20. — For strengthening 
the leg below the knee and de- 
veloping the calf, stand erect, and 
rise and sink slowly on toes and heels a great many 
times (see Fig. 107). 

Exercise 21. — Stand on one foot and raise the other 
leg, bending the knee (see Fig. 108). Bend and 
straighten several times. . Eepeat with the other leg. 

Exercise 22 — An excellent exercise for the legs and 
body muscles is to place one 
foot forward as if stepping. 
Then rising on the toes, spring 
lightly back and forth, alter- 
nating the position of the 
feet. 

GAMES AND SPORTS 

The great value of games 
and sports, aside from the Fig. 106. 




330 



PHYSIOLOGY AND HYGIENE 



pleasure we take in them and the muscular development 
they give, is in the training of the senses and the mind. 
We learn to think quickly and to be alert in our move- 
ments. We also come to see how important 
it is to be fair in our treatment of others. 

Since each game or sport trains only cer- 
tain sets of muscles, and requires its own 
particular kind of effort, it is well to be 
familiar with a variety of such pastimes. 

Running is especially good for strengthen- 
ing the muscles of the legs; it also compels 
us to breathe deeply. 

Jumping develops the legs and the ab- 
dominal muscles, and also the muscles of 
the shoulders and chest. 

Baseball combines all the good qualities of 
these two sports. 
Swimming is perhaps the most val- 
uable sport of all, for it exercises a 
great many different sets of muscles. 
All strokes should be practiced, and 
also swimming on the back. Every 
boy and girl should know how to 
swim, not only because it is good 
exercise, but so that in case of acci- 
dents, which occur very frequently 
on the water, one could save himself 
or rescue others from danger. 

Tennis — Tennis exercises the legs 
and ankles, and also the muscles of fig. 108. 




Fig. 107. 




HOW TO DEVELOP OUR BODIES 



331 




the body, but the right arm is likely to be developed at 
the expense of the left. In striking the ball, a long easy 
swing of the arm should be cultivated. Handling the 
racquet gives excellent exercise to the wrist. 

Skating. — Skating is almost as good for exercise as 
swimming. It not only gives exercise to the muscles 
of the legs, but in the long, sweeping " strokes " the 
muscles of the waist and abdomen are brought into 
constant use. The 
arms help in keep- 
ing the balance, 
and the vigorous 
exercise in the 
cold, bracing air 
makes one breathe 
deeply and so de- 
velop the lungs 
and chest. Ice 
hockey is a good 
skating game, al- 
though hockey, of course, can be played in a field as 
well as on the ice. 

Hammer throwing and shot putting are two excellent 
sports. We cannot explain the scientific points here, 
but perhaps a few directions will show how these sports 
develop the muscles. 

Hammer Throwing. — The thrower must stand in a 
circle seven feet in diameter, feet apart, body bent for- 
ward and well balanced. The head of the hammer 
(a stick with a heavy weight fastened to the end may 




Fig. 109. — Hammer Throwing. 



332 PHYSIOLOGY AND HYGIENE 

be substituted) should rest on the ground back of the 
thrower. The weight of the hammer should not be 
so great as to strain the arms and shoulders. It is 
better to start with a light hammer and increase the 
weight from time to time. 

Shot Putting. — The player stands in a ring as before, 
left foot forward and weight resting on the right foot. 
The shot (a large, smooth stone will do) held up in the 
right hand, the right elbow being bent so that the upper 
arm rests against the side. When ready to throw, slide 
the left foot forward quickly and back, then fling the 
whole right side forward as the shot is thrown. 

ALCOHOL AND ATHLETICS 

Men who are being trained for athletic contests are 
forbidden by their trainers to use alcoholic drinks, 
smoke cigarettes, or use tobacco in any form, because 
these stimulants and narcotics affect the action of the 
heart and prevent the contestants from carrying on 
sustained muscular effort. Alcohol in excess interferes 
with the heart and the circulation of the blood and 
impairs the action of the digestive organs. It also 
weakens one's moral powers. 

Inhaling the smoke of cigarettes not only may cause 
heart trouble, but prevents proper growth of the body 
and lowers the resistant powers to disease. Therefore, 
if a boy wishes to be strong in body and alert in mind 
he should be like the athlete in training, using neither 
alcohol nor tobacco. 



GLOSSARY OF TECHNICAL TERMS 

ab-do'men. — The lower cavity of the body containing the stomach, 

intestine, and other organs, 
ab'scess. — A sore that comes to a head and discharges pus. 
a-dul'ter-a'tion. — The debasing of a product by the addition of an 

impurity, 
al-bu'men. — A proteid, like the white of egg. 
an-te'ri-5r root. — The branch of a spinal nerve that carries messages 

from the brain to the muscles. See Fig. 67. 
an'ti-dote. — Anything that will counteract the effects of a poison, 
an'ti-sep'tic. — A substance capable of destroying germs. 
an'-tl-tSx'In. — A substance which neutralizes poison produced by 

germs, 
a-or'ta. — The artery carrying blood from the heart. See Fig. 21. 
a/que-ous hu'mo'r. — One of the transparent liquids in the eye. See 

Fig. 75. 
ar-te'ri-al blood. — Blood that has been purified by passing through the 

lungs. 
ar'ter-y. — A blood vessel carrying blood away from the heart. 

ba-cU'liis. — One type of bacteria. 

bac-te'ri-a. — A group of very minute plants. 

ball-and-s5ck'et joint. — A joint allowing free motion in all directions. 

See Fig. 53. 
bi'ceps. — The front muscle of the upper arm. See Fig. 55. 
bi-cus'pids. — Eight of the teeth, four in each jaw, between the canines 

and the molars. See Fig. 9. 
bile. — The liquid secreted by the liver. 

blad'der. — The sac that temporarily holds the kidney secretion, 
blood heat. — The ordinary temperature of the body, 98.5° F. 
bow'els. — The intestine. 

breast bone. — The bone in front of the chest. See Fig. 42. 
brSn'chi. — The branches of windpipe entering the lungs. See Fig. 33. 



334 PHYSIOLOGY AND HYGIENE 

cal-los'i-ties. — Parts of the epidermis thickened by friction, 
ca'nlnes. — Four teeth, just back of the incisors. See Fig. 9. 
cap'il-la-ries. — The small blood vessels connecting the arteries with 

the veins. See Fig. 25. 
car'bon di-bx'ide. — The gas that results from the burning of carbon in 

oxygen. 
car-5t'id. — The large artery in the neck. See Fig. 22. 
car'pals. — The wrist bones. See Fig. 42. 
car'ti-lage. — The tough flexible material that forms the softer part of 

the skeleton. See Figs. 33, 42, 60. 
ca'se-in. — A proteid in milk, the basis of cheese. 
ca-tarrh'. — A disease of the nasal cavity and throat. 
cau'ter-ize. — To burn, usually for the purpose of destroying infectious 

material. 
cell. — One of the microscopic bits of living matter of which the whole 

body is composed, 
ce're-als. — Food materials obtained from grain, such as wheat, oats, 

rice, etc. 
cer'e-bel'lum. — The back part of the brain. See Fig. 65. 
Ser'e-briim. — The highest and largest part of the brain. See Fig. 65. 
chest, or tho'rax. — The cavity within the ribs, which holds the lungs 

and heart. See Fig. 38. 
cho'roid. — The middle coat of the eyeball. See Fig. 75. 
chyle. — The food in the intestine, after it is thoroughly digested. 
chyme. — The food mass as it leaves the stomach, 
clav'i-cle. — The collar bone. See Fig. 42. 
co-ag'u-la'tion. — A change from a liquid to a solid condition, such as 

that which occurs in the white of an egg when heated. 
ccVcyx. — A small piece of bone at the lower end of the spinal column. 
cSm-mu'm-ca-ble. — Capable of being transmitted from person to per- 
son, 
com 'press. — A mass of soft cloth arranged with a bandage to produce 

pressure upon any part. 
cbn-ta/gious. — Easily passed from person to person, 
cbn-trac'tion. — Shortening. 

cSn'vo-lii'tions. — The folds in the surface of the brain, 
cords. — See tendons, 
corn. — A thickened portion of the epidermis (usually on a toe) caused 

by friction or pressure. 
cor'ne-a. — The transparent covering of the eyeball, in front. See Fig. 

75. 



GLOSSARY OF TECHNICAL TERMS 335 

c5r'pus-cle. — A small body. 

cra'ni-um. — The rounded part of the skull, containing the brain. See 
Fig. 44. 

der'mis. — The inner layer of the skin. See Fig. 61. 

dl'a-phragm. — A tough, muscular membrane separating the thorax 

and abdomen. See Fig 38. 
diph-the'ri-a. — A very serious disease of the throat, 
dis'in-fec'tion. — Destroying the germs of disease, 
dls'lo-ca/tion. — The wrenching of bones out of position, 
dis-tilled' liq'ub'rs. — Liquors made by separating the alcohol from a 

fermenting substance. 
duct. — A slender tube by which secretions are carried from a gland. 

See Fig. 11. 
dys-pep'si-a. — A disease of the digestive organs. 

ear'dnim. — The middle cavity of the ear. See Fig. 76. 

en-am'el. — The outer hard covering of the teeth. 

ep'i-dem'ic. — Any disease spreading among a great number of people. 

ep'i-der'mis. — The outer layer of the skin. See Fig. 61. 

ep'i-gl5t'tis. — The lid covering the opening into the windpipe. See 
Fig. 12. 

ep'i-the'li-um. — A layer of cells covering the various internal and ex- 
ternal surfaces of the body. See Fig. 12. 

Eu-sta'chi-an tube. — A tube leading from the upper part of the throat 
to the middle ear. See Figs. 12 and 76. 

ex-cre'tion. — Waste material passed from the body. 

ex'ha-la'tion. — Breathing air out of the lungs. 

fat cell. — A minute drop of fat such as exists in meat. See Fig. 2. 
fe'mur. — The bone extending from the hip to the knee. See Fig. 42. 
fer'men-ta'tion. — A change occurring in sugar solutions by which 

alcohol is produced, 
fer-men'ted Hq'u<5rs. — Drinks made from simple fermented material, 
fi'bers. — Minute threads, like those of muscles or nerves, 
flushed. — Red from the expansion of blood vessels. 
fo-ra'men 6-va'le. — The opening from the middle ear into the inner 

ear. See Fig. 76. 
f rbnt'al bone. — The bone forming the forehead. See Fig. 44. 
fu'el foods. — Foods used to develop force or heat. 
fu'ml-ga'tion. — Treating with fumes of gas, usually to destroy disease 

germs. 



336 PHYSIOLOGY AND HYGIENE 

gall-blad'der. — A sac which collects the bile secreted by the liver. 

See Fig. 13. 
gan'gli-6'n. — A mass of nerve tissue containing nerve cells. See Fig. 

67. 
gas'tric juice. — The digestive fluid secreted by the glands of the 

stomach, 
gltft'tis. — The opening from the throat into the windpipe. See Fig. 

12. 
glu'c5se, or grape sugar. — Sugar found, or similar to that found, in 

fruits. 
glu'ten. — A proteid derived from wheat and some other substances. 
grav'i-ty. — The force that pulls objects toward the earth, 
gris'tle. — The name given to cartilage when cooked, as in meat. 
gul'let. — See oesophagus. 

hae'mo-glo'bin. — The red coloring matter in blood. 

hair fol'li-cles. — The little pockets from which hairs grow. See Fig. 

62. 
hard water. — Water containing some mineral substance, usually lime. 
hem/I-spheres. — The two halves of the cerebrum. See Fig. 66. 
hi'ber-nat'mg. — Kemaining in a dormant, sleeping condition during 

the winter months, 
hinge joint. — A joint in which the bones can move in one direction 

only. See Fig. 52. 
hu'mer-iis. — The bone extending from the shoulder to the elbow. See 

Fig. 42. 

il'i-um. — One of the bones of the pelvic girdle. See Fig. 42. 

lm-mu'ni-ty. — Ability to resist disease. 

In-ci'sors. — The eight middle front teeth. See Fig. 9. 

in'ciis. — One of the bones of the ear. See Fig. 76. 

in'di-ges'tion. — Inability properly to digest food. 

In-f ec'tious. — Produced by germs, usually contagious. 

ln'flam-ma'tion. — A condition of enlarged blood vessels, accompanied 

by heat and soreness in the inflamed part. 
m'hal-a'tion. — Breathing air into the lungs. 
In-oc'u-late. — To introduce infectious matter. 
in-tes'tine. — The tube through which food passes after leaving the 

stomach. See Fig. 13. 
in-voVun-ta-ry\ — Without the exercise of will power. 
I'ris. — The colored membrane around the pupil of the eye. 



GLOSSARY OF TECHNICAL TERMS 337 

Is'chi-um. — One of the bones of the pelvis. See Fig. 42. 
i'so-la'tion. — Keeping a patient away from other persons to prevent 
his giving them disease. 

kid'neys. — The organs for removing the waste products found in the 
urine. See Fig. 60. 

lach'ry-mal duct. — The duct which carries tears from the eyes to the 
nasal cavities. See Fig. 72. 

lach'ry-mal gland. — The gland that secretes the tears. 

lac'te-als. — Small tubes that carry fat from the intestines to the blood 
vessels. See Fig. 16. 

lar'ynx, or Ad'am's ap'ple. — An enlarged part of the windpipe con- 
taining the vocal cords. See Fig. 12. 

lig'a-ments. — Bands of white connective substance, which join bones. 
See Figs. 51 and 52. 

lig'a-ture. — A band drawn tightly around some part of the body to 
stop bleeding. See Fig. 30. 

lime. — A mineral substance for making bone. 

liv'er. — A large red gland lying near the stomach. See Fig. 13. 

lungs. — Two organs in the chest cavity which absorb oxygen and give 
off carbon dioxide. 

lymph ves'sel. — A minute tube that carries lymph. 

ma-la'ri-a. — A disease accompanied by chills and fever. 

mal'le-iis. — One of the bones of the ear. See Fig. 76. 

man'di-ble. — The jaw bone. See Fig. 44. 

mar'row. — A fatty material in the middle of the long bones. See Fig. 

45. 
mas'ti-cate. — To chew. 

me-diil'la. — The lowest part of the brain. See Fig. 65. 
med'iil-la-ry sheath. — The covering of the axis cylinder of a nerve. 

See Fig. 67. 
mem'brane. — Soft tissue in the form of a sheet or a layer covering 

some part of the body, 
mes'en-te-ry. — A membrane wrapped around the intestine and filled 

with blood vessels. See Fig. 16. 
met 'a-car 'pals. — The bones between the wrist and the fingers. See 

Fig. 42. 
met' a -tar'sals. — The bon s between the ankle and the toes. See Fig. 

42. 



338 PHYSIOLOGY AND HYGIENE 

mo'lars. — The large back teeth, twelve in number. See Fig. 9. 
mumps. — A disease accompanied by swollen jaws and cheeks. 
muscle fi'bers. — The microscopic threads of which muscle is made. 

See Fig. 58. 
my'o-sm. — A proteid found in meat. 

nar-cSfic. — A drug that dulls body action. 

na'sal. — Pertaining to the nose. 

nerve cells. — Minute bodies at the ends of nerve fibers which cause 

and receive stimuli. See Fig. 69. 
nerve fi'bers. — The microscopic threads of which a nerve is composed. 

See Fig. 68. 
nerves. — Long bundles of fibers that carry messages in the body. 
neu'tra-lize. — To counteract or destroy the effect of. 
nl-trog'e-nous. — Foods containing nitrogen. 
nu-tri'tious. — Capable of building up the body or furnishing it with 

heat or force. 

8c-cl'pi-tal. — The bone forming the back of the skull. See Fig. 44. 
ce-soph'a-gus, or gul'let. — A tube extending from the throat to the 

stomach. See Fig. 13. 
ox'i-da'tion. — A union of some substance with oxygen. 
dx'y-gen. — A gas forming one fifth of the air. 

pal 'ate. — The roof of the mouth. 

pan'cre-as. — A large gland which secretes a fluid to digest proteids, 
starches, and fats. See Fig. 13. 

pap-il'la. — A minute, finger-like projection. 

par'a-site. — An animal or plant that lives on the body of another ani- 
mal or plant. 

pa-ri'e-tals. — The bones forming the sides of the cranium. See Fig. 44. 

par St'id glands. — The salivary glands in front of the ear. 

pa-tel'la. — The round bone in front of the knee. See Fig. 42. 

pel 'vis, or pel'vic gir'dle. — The hip bone. See Figs. 38 and 42. 

pe'trous bone. — The very hard bone that contains the ear. 

pha-lan'ges. — A name given to the bones of the fingers and toes. 

phlegm. — A thick, jelly-like material secreted by the air passages or 
the stomach. 

pil'lars of the f au'ces — Two curtain-like sheets between the mouth 
and the throat. See Fig. 10. 

plas'ma. — The liquid part of the blood. 



GLOSSARY OF TECHNICAL TERMS 339 

pneu-m5'ni-a. — A very serious disease of the lungs. 

pores. — Small openings in the skin through which the sweat passes. 

p5s-te'rior root. — The branch of the spinal nerves which carries mes- 
sages from the skin and muscles to the brain. 

pre-ser'va-tives. — Chemical substances added to food materials to pre- 
vent their spoiling. 

pro'te-ids. — Foods useful for building body tissue, such as albumen, 
gluten, etc. 

pu'bis. — One of the bones of the pelvic girdle. See Fig. 42. 

piil'mo-na-ry ar'te-ry. — The artery which carries blood from the heart 
to the lungs. See Fig. 23. 

piil'mo-na-ry clr-cu-la'tion. — The circulation of the blood from the 
heart to the lungs and back. 

pulse. — A wave of pressure that passes along the arteries with each 
heart beat. 

pu'pil. — The circular opening in the front of the eye that allows light 
to pass into the eye. 

rab'id. — Suffering from rabies, or hydrophobia. 

ra'di-iis. — One of the bones of the forearm. See Fig. 42. 

re'flex ac'tions. — Actions that take place without the exercise of the 

will. 
ren'net. — A ferment secreted by the stomach, which curdles milk, 
res'pi-ra'tion. — The absorption of oxygen and elimination of carbon 

dioxide by the lungs. 
ret'i-na. — The sensitive surface at the back of the eye. See Fig. 75. 

sa'crum. — The part of the spinal column between the hips. 

sa-li'va. — The secretion that moistens the mouth. 

sal'i-va-ry glands. — The glands that secrete saliva. See Fig. 11. 

scap'u-la. — The bone of the shoulder blade. See Fig. 42. 

scarlet fe'ver. — A disease characterized by a pinkish eruption of the 

skin. 
scle-rSt'Ic. — The outer coat of the eyeball. See Fig. 75. 
se-cre'tion. — Material produced by a gland for the use of the body. 
sem'I-lu'nar valves. — Three valves in the large arteries near the heart, 
sen'sd-ry nerves. — Nerves that carry messages to the brain resulting 

in sensations, 
spi'nal cord. — The part of the nervous system which extends down 

within the backbone. See Figs. 43 and 66. 
spi'nal nerves. — Nerves arising from the spinal cord. 



340 PHYSIOLOGY AND HYGIENE 

spine. — The name given to the backbone. 

spleen. — A good-sized gland in the abdomen. See Fig. 13. 

sprain. — The tearing or straining of ligaments at a joint. 

spu'tum. — Matter spit up from the throat or lungs. 

sta'pes. — One of the bones of the ear. See Fig. 76. 

starch grains. — The minute bits of starch as they are found in the 

potato and other raw foods, 
ster'i-liz-ing. — Heating a substance until all living organisms (bacteria) 

are killed. 
ster'num. —The breastbone. See Fig. 42. 
stim'u-hls. — A shock that causes a muscle or other organ to act. 
stif fd-ca'tion. — Stopping of breathing by closing the windpipe or by 

some other means, 
sys-tem'ic cir'cu-la'tion. — The circulation in all of the body except 

the lungs. 

tar'sals. — The ankle bones. See Fig. 42. 

taste buds. — The organs of taste in the tongue. 

ten 'dons. — Bands of white substance uniting muscles with bones. See 

Fig. 56. 
tho'rax. — The chest. 
thr5at. — The cavity at the back of the mouth into which the mouth 

and nose open. See Fig. 12. 
tib'i-a. — The large bone extending from the knee to the ankle. See 

Fig. 42. 
ton'sils. — Two rounded bodies at the back of the mouth. See Fig. 10. 
t6n-si-H'tis. — A disease of the throat, accompanied by sore throat and 

fever. 
toVin. — A poison produced by a germ, 
tra'che-a. — The windpipe. 

tym-pan'ic cav'i-ty. — The ear drum or middle ear. 
tym-pan'ic mem'brane. — A membrane stretched across the passage 

leading to the ear. See Fig. 76. 

iil'na. — One of the bones of the forearm. See Fig. 42. 

ii're-a. — The chief waste product of muscle action, secreted by the 

kidneys, 
u-re'ter. — The duct leading from the kidney to the bladder. See 

Fig. 60. 
u'vu-la. — A small piece of the soft palate hanging downward from the 

back of the mouth. See Fig. 10. 



GLOSSARY OF TECHNICAL TERMS 341 

vac'ci-na'tion. — Treatment designed to prevent smallpox. 

valve. — A mechanism to open and close a passage. 

va'sS-mo'tor nerves. — Nerves controlling the size of the small blood 

vessels. 
vein. — A blood vessel carrying blood toward the heart, 
ve'nous blood. — Blood made impure by gathering up the wastes of the 

body, 
ven'tri-cles. — The chambers of the heart that send blood into the 

arteries. See Fig. 23. 
ver'mi-form ap-pen'dix. — A small projection from the end of the large 

intestine. See Fig. 13. 
ver'te-bra. — One of the bones composing the spine. See Fig. 43. 
vil'li. — Little projections on the inside of the intestine for absorbing 

food. See Fig. 17. 
vit're-ous hu'mo'r. — One of the transparent media of the eye. See 

Fig. 75. 
vo'cal cords. — Two membranes in the larynx whose vibrations produce 

the voice. 

yeast. — Microscopic plants that cause the fermentation of sugar. 



INDEX 



Abdominal muscles, Exercises 

for, 328. 
Abscesses, 240, 269. 
Acid poisons, 314. 
Adulterated foods, 296. 
Air, as a distributor of bac- 
teria, 244, 295. 

Need of fresh, 117, 283. 

passages, 105. 

sacs, 108. 
Albumen, 14. 
Alcohol, 27, 100, 184. 

and consumption, 287. 

Appetite for, 70, 186. 

Use of, 30, 69, 86, 101, 184, 
246-249, 332. 
Ale, 29. 

Animal tuberculosis, 290. 
Antidotes to poisons, 313. 
Antitoxin, 257. 
Appetite as a guide, 68. 
Arms, Exercises for, 326. 
Arsenic poisoning, 314. 
Arteries, 83, 87, 91. 

Location of, 89. 
Artery, Pulmonary, 84. 
Artificial breathing, 121. 
Auditory nerve, 224. 
Auricles, 83. 

Back, Exercises for, 327. 

Backbone, 126, 133. 

Bacteria, 25, 163, 239, 279, 291. 

how carried, 243, 293, 295. 

how they get out of the 
body, 242, 280. 

Protection against, 240, 
252, 281, 285, 292. 
Baking, 77. 

powder, 78. 
Balance of the body, 321. 
Ball-and-socket joints, 138, 139. 
Bananas, 23. 



Bar and Ring exercise, 327. 
Baseball, as exercise, 330. 
Baths, 172, 237. 

Cold, 172. 

Hot, 175. 
Beans, 23. 
Beef tea, 74. 
Beer, 29. 
Beets, 23. 

Biceps muscle, 141. 
Bicuspid teeth, 38. 
Bile, 54. 

Bites of animals, 273, 308. 
Bladder, 156. 
Bleeding, 90. 

how stopped, 91. 
Blisters, 158. 
Blood, 80. 

Circulation of, 80. 

Clotting of, 93. 

Impure, 89. 

poisoning, 269. 

Pure, 89. 

Respiratory changes in, 113. 
Blood vessels, 87. 

of lungs, 108. 

of skin, 100, 162. 

Regulation of, 97, 191, 203. 
Blushing, 99. 
Boards of Health, 291. 
Body, Development of the, 316. 

Dangers of unequal, 318. 

Importance of, 317. 

Results of, 333. 
Boiling, 57, 76, 295. 
Boils, 240, 269. 
Bones, 124, 128. 

Broken, 132, 237. 

Carpal, 125. 

how held together, 136. 

List of, 152. 

Material for, 18, 128. 

Misshapen, 130. 



342 



INDEX 



343 



Bones — continued. 

of children, 129. 

Structure of, 128. 
Bowels, 53. 

Brain, 96, 99, 145, 166, 189, 190. 
Brandy, 30. 
Bread raising, 78. 
Breastbone (see Sternum). 
Breathing, 110. 

and exercise, 115. 

Artificial, 121. 

Center of, 191, 202, 203. 

Exercises for, 112, 321. 

Process of, 321. 

Purpose of, 113, 318, 322. 

through mouth, 105, 318. 
Broiling, 57, 78. 
Bronchus, 107. 
Burns, Treatment of, 177. 
Butter, 17, 19. 

Callosities, 158. 
Candy, 67, 229. 
Canine teeth, 38. 
Capillaries, 87, 88. 

of lungs, 108. 

of muscles, 153. 
Carbolic acid, 303, 314. 
Carbon dioxide, 104, 113, 115. 
Carpal bones, 125, 152. 
Cartilage, 133. 
Casein, 14. 
Cereals, 21, 67. 
Cerebellum, 191. 

Duties of the, 203. 
Cerebrum, 191. 

Duties of the, 204. 

Hemispheres of the, 192. 
Character, and physical train- 
ing, 300. 
Cheeks, 37. 
Cheese, 19. 
Chest, 109, 327. 
Chicken pox, 241. 
Chilblains, 179. 
Chills and fever, 239. 
Chloral, 182. 
Chloride of lime, 302. 
Chocolate, 27, 67. 
Choking, 306. 



Cholera, 263. 

Cholera mixture, 314. 

Chyle, 56. 

Chyme, 51. 

Cider, 29. 

Cigarettes, 183. 

Circulation of blood, 80, 89. 

Clavicle, 125, 152. 

Cleanliness, 172. 

Clothing, 176. 

Clotting of blood, 93. 

Cocaine, 182. 

Cocoanuts, 23. 

Coffee, 26. 

Cold, Sensation of, 99, 233. 

Taking, 117, 169. 
Cold-blooded animals, 166. 
Colds, 117, 169, 237. 
Color blindness, 220. 
Concentration of thought, 208. 
Consumption, or tuberculosis, 

20, 117, 277. 
Consumptives, Precautions for, 

287. 
Contagious diseases, 238, 242. 

Immunity from, 241. 

Prevention of, 242. 

Spread of, 300. 
Cooking, Purpose of, 72. 

Methods of, 76. 

Principles of, 74. 
Cords, 137, 141. 
Corn, 21, 22, 28. 
Corns, 158. 
Corpuscles of blood, red, 81 ; 

white, 82. 
Corrosive sublimate, 302, 314. 
Cottonseed oil, 17. 
Coughing, 45, 202, 244, 246. 
Cramps, 307. 
Cuts, Treatment of, 163, 272. 

Deafness, 224, 226. 
Dermis, 157, 162. 
Diaphragm, 110. 
Digestibility of foods, 56. 
Digestion, 37, 49. 

in the intestines, 55. 

in the mouth, 43. 

in the stomach, 49. 



344 



INDEX 



Diphtheria, 20, 240, 257, 300. 
Direction of sound, how judged, 

225. 
Diseases, 238. 

Contagious, 238, 253. 
Distribution of, 20, 293, 

295, 297, 300. 
Germs, source, 255. 
Immunity from, 241. 
Parasitic, 238. 
Disinfection, 301, 304. 
Dislocation of joints, 140. 
Distance of sound, how judged, 

225. 
Distilled liquors, 29. 
Dogwood poisoning, 310. 
Drowning, Treatment in case 

of, 120. 
Dumb-bells, 327. 

Ear bones, 224. 

drum (see Tympanic cav- 
ity). 

Middle, 222. 
Ears, 222. 

Care of, 225. 
Ease of motion, 325. 
Eating, Pleasure in, 68. 

Time of, 66. 
Eggs, 21, 67. 

Electricity, Accidents from, 311. 
Emergencies, 305. 
Epidermis, 157. 

Thickened parts of, 158. 
Epiglottis, 44, 45, 106. 
Epithelium, 60. 
Erysipelas, 269. 
Eustachian tube, 44, 222. 
Excretions, 154. 
Exercise, Need of, 148, 317. 
Exercises, for breathing, 112, 
321. 

for development of various 
muscles, 326. 
Eye, 217. 
Eyeball, 214, 216. 

Size of, 214. 
Eyelashes, 215. 
Eyelids, 215. 
Eyes, Care of, 220. 



Fainting, 95. 
Fat, 17, 153. 

Absorption of, 61. 

cells, 17, 157. 

Digestion of, 56. 
Feeling, 231. 
Femur, 125, 134, 152. 
Fermentation, 27. 
Fermented liquors, 29. 
Fever, Scarlet, 20, 240, 241. 

Typhoid, 20, 240, 260, 275, 
393. 

YeUow, 241. 
Filtering, 295. 
Finger nails, 161. 
Flavor, Use of, 26. 

produced by bacteria, 240. 

produced by cooking, 72. 
Flies as disease distributors, 267. 
Flour, 21. 
Fly powders, 314. 
Food, Absorption of, 58-62. 

Amount of, needed, 31. 

habits, 65. 

Kind of, 13. 

Mastication of, 42. 

Purposes of, 11. 

Uncooked, as a distributor 
of disease, 245. 

values, 32. 

value tables, 33, 34, 35. 
Foods, Adulteration of, 296. 

Cost of, 32, 66. 

Digestibility of, 56. 

for building purposes, 12, 
19 32. 

for fuel, 13, 15, 19, 153. 

Inspection of, 292, 296. 

Preservatives used in, 297. 

Source of, 18. 

Undigested portions of, 62. 
Formalin, 302. 

Frostbites, Treatment of, 178. 
Fruits, 23, 67. 
Frying, 58, 78. 
Fumigation, 304. 

Gall bladder, 47, 54. 
Games and sports, 317, 330. 
Ganglion, 193. 



INDEX 



345 



Garbage, 297. 
Gastric juice, 49. 
Germs (see Bacteria). 
Gin, 30. 
Glands, 155. 

Ducts of, 42. 

Gastric, 48, 155. 

Lachrymal, 214. 

of tongue, 227. 

Pancreatic, 54. 

Salivary, 41, 155. 

Sweat, 157, 163, 169. 

Tear, 215. 
Glottis, 44, 45. 
Gluten, 14. 
Graham meal, 21. 
Grape juice, 29. 

Gravity, Effect of, on circula- 
tion, 95. 
Grip, 259. 
Gullet, 45. 

Habits, Acquiring of, 205. 
Hair, 159. 

Follicle of, 159. 
Hammer throwing, 331. 
Hands, Exercises for, 328. 
Health, Disease and, 237. 

Duty of preserving, 249. 

Boards of, 292. 
Hearing, Sense of, 222, 224. 
Heart, 82. 

Beating of, 85. 

Center of control of, 191, 
203. 

Regulation of, 96. 

Valves of the, 85. 
Heat prostration, 312. 
Hemoglobin, 82. 
Hibernating animals, 167. 
Hinge joints, 134, 137. 
Hookworm, 262. 
Hospitals, 304. 
Humerus, 125, 138. 
Hunger, 68, 231. 
Hydrophobia, 273. 
Hygiene, Personal and Public, 
291. 

Immunity, 275. 



Incisors, 38. 
Incus, 222. 
Indian meal, 21. 
Indoor life, Evils of, 117. 
Inflammation, 269. 
Influenza, 259. 

Insects as distributors of dis- 
ease, 245. 
Inspection, 292. 

of food, 296. 

of ventilation, 295. 

of water, 293. 
Inspiration, 111. 
Intemperance, 72, 250. 
Intestines, 47, 53. 
Involuntary muscles, 143, 145. 
Isolation, 300. 
Ivy poisoning, 309. 

Japanese, The, and preventable 

diseases, 254. 
Joints, 134. 

Ball-and-socket, 138. 

Dislocation of, 140. 

Hinge, 134, 137. 

Injuries at, 139. 

Knee, 134. 

Shoulder, 138. 
Jumping, 330. 

Kidneys, 155. 

Tubules of the, 156. 

Lachrvmal duct, 214. 

gland, 214. 
Lacteals, 62. 
Lard, 17. 

Larynx, 44, 106, 107, 133. 
Laudanum, 181, 314. 
Lead poisoning, 314. 
Legs, Exercises for, 329. 
Lens of eye, 217. 
Lentils, 23. 

Ligaments, 135, 136, 139. 
Lime, 18, 26. 
Liquors, Distilled, 29. 

Fermented, 29. 
Liver, 53. 

Duties of the, 54. 
Lockjaw, 271. 



346 



INDEX 



Lung diseases associated with 

impure air, 117. 
Lungs, 106. 

Capacity of, 111. 

Exercise of, 112. 
Lymph vessels, 62. 

Malaria, 239, 264. 

Malleus, 222. 

Malt, 28. 

Meals, Frequency of, 66. 

Measles, 240, 268, 300. 

Meats, 20. 

Cooking of, 73. 

Digestion of, 49. 
Medicines, 237. 
Medulla oblongata, 191. 

Duties of the, 202. 
Mercury poisoning, 314. 
Mesentery, 58. 
Metacarpals, 125, 152. 
Metatarsals, 125, 152. 
Middle ear, 222. 
Milk, 19. 

Curdling of, 51. 

Digestion of, 51. 

Diseases distributed by, 20, 
261. 

Inspection of, 292. 
Mind, Dependence of, on body, 
210. ' 

Care of the, 207. 
Mineral substances, 26. 
Molar teeth, 38. 
Molasses, 28. 
Morphine, 181. 
Mosquito bites, the cause of 

malaria, 239, 264. 
Motor centers, Location of, 206, 
207. 

nerve fibers, 200. 
Mouth, 37. 

-breathing, 105. 
Mumps, 240, 241, 259, 300. 
Muriatic acid poisoning, 314. 
Muscle, Biceps, 141. 

fibers, 142. 

sense, 235. 
Muscles, 141. 

at joints, 137, 139. 



Muscles — continued. 

Contraction of, 144, 145. 

Developing of, 317. 

Growth of the, 147. 

Involuntary, 143, 145. 

Number of, 146. 

of blood vessels, 97. 

of breathing, 109. 

of eye, 216. 

Structure of, 141. 
Myosin, 14. 

Nails of fingers and toes, 161. 
Narcotics, 180. 

Effect of, upon mind, 210. 
Nasal cavities, 41, 44, 230. 
Nearsightedness, 219. 
Neck, Exercises for, 328. 
Nerve cells, 195. 

fibers, 145, 194. 

trunks, 194. 
Nerves, 96, 190, 194. 

Anterior root of the, 194. 

Duties of the, 198. 

Motor, 200. 

of hearing, 224. 

of muscles, 145. 

of nose, 230. 

of retina, 218. 

of skin, 157, 162. 

of tongue, 227. 

Posterior root of, 194 

Sensory, 200. 

Vaso-motor, 99. 
Nervous system, 189. 
Night air, 118. 
Nitric acid poisoning, 314. 
Nitrogenous foods, 14. 
Nosebleed, 306. 
Nuts, 23. 

Oatmeal, 21, 67. 
Oats, 21, 22. 
(Esophagus, 44, 45. 
OH glands, 160. 
Olfactory nerve, 230. 
Olive oil, 17. 
Opium, 181, 314. 
Optic nerve, 216, 218. 
Organic matter, 18. 
Overindulgence, 72, 250. 



INDEX 



347 



Oxalic acid poisoning, 314. 

Oxidation, 104, 153. 

Oxygen, 13, 104, 113, 115, 116, 

318. 
Use of, 114. 
Oysters, as disease distributors, 

262. 

Pain sense, 234. 
Palate, 37, 44. 
Pancreas, 47, 54, 155. 
Papillae of hair, 159. 

of tongue, 227. 
Paragorie, 181, 314. 
Parasites, 73. 
Parasitic animals, 239. 

bacteria, 239. 

diseases, 238. 
Paris green, 314. 
Peanuts, 23. 
Peas, 23. 

Pelvic girdle, 125. 
Phosphorus, 315. 
Physical training (see Body, 

Development of). 
Piano, Learning to play the, 203. 
Pink eve, 274. 
Plague, 267. 

Plumbing, Importance of, 243. 
Pneumonia, 117, 260. 
Poise, 320. 

Poisoning, Treatment for, 313. 
Pores of skin, 164. 
Position in sitting, 319. 

in standing, 287, 320. 

in walking, 324. 
Potatoes, 23, 32. 

Cooking of, 73. 
Preservatives in foods, 297. 
Pressure, Sense of, 231. 
Preventable diseases, 252. 
Proteids, 14, 153. 

Absorption of, 61. 

coagulated by heat, 74. 

Digestion of, 50, 55. 

Need of, 50, 55. 

Source of, 33, 34, 35. 
Pulmonary artery, 84. 
Pulse, 86. 
Pupil of the eye, 217. 



Quarantine (see Isolation). 

Rabies, 273. 

Radius, 125, 152. 

Recreation, 209. 

Reflex action in spinal cord, 201. 

in medulla, 202. 
Rennet, 51. 
Repair of body, 12. 
Reservoirs, Care of, 294. 
Respiration, 105, 115. 

Restoration of, 120. 
Retina, 217. 

Ribs, 125, 127, 133, 152. 
Rice, 21, 22. 
Roasting, 57, 77. 
Rubbing, 174, 237. 
Rum, 30. 
Running, 330. 
Rye, 21. 

Saliva, Use of, 41, 43. 

Salivary glands, 41, 155. 

Salt, 26. 

Sauces, 229. 

Scapula, 125, 138, 152. 

Scarlet fever, 20, 240, 241, 268, 

300. 
Secretions, 154. 
Sensations, 213. 

Location of, in brain, 199, 
207. 
Sense organs, 214. 
Senses, 213, 231. 
Sensory nerve fibers, 200. 
Sewage, 243, 294, 297. 
Sewerage systems, 299. 
Shoes, 131. 
Shot putting, 332. 
Shoulder joint, 138. 
Shoulders, Exercises for, 327. 
Sick room, Care of, 303. 
Sight, Sense of, 214. 
Sitting, Importance of correct, 

319 
Skating, 331. 
Skeleton, 124, 125. 
Skin, 156. 

Care of, 172. 

Functions of, 163. 



348 



INDEX 



Skin — continued. 

Sensations of, 231. 

Structure of, 156. 
Skull, 127. 
Sleep, 207. 

Smallpox, 241, 268, 300. 
Smell, Sense of, 214, 229. 

Duration of, 231. 

Location of, 230. 

Use of, 230. 
Snake bites, Treatment of, 308. 
Soothing sirup, 181, 314. 
Sore throat, 46. 

Sound, Direction of, how judged, 
225. 

Distance of, how judged, 
225. (See Hearing.) 
Soups, 75. 
Special senses, 214. 
SpiDal cord, 126, 192, 201. 

Duties of, 200. 

Gray matter of, 193. 

White matter of, 193. 
Spine (see Backbone). 
Spitting, Dangers of, 280. 
Sports and games, 329. 
Sprain, 140. 
Sputum, 280. 
Standing, Correct position in, 

320. 
Stapes, 222. 
Starch, 15. 

Absorption of, 61. 

Digestion of, 43, 55. 
State Board of Health, 292. 
Sternum, 125, 127. 
Stews, 75. 

Stimulants, 149, 180. 
Stimulus, 145. 
Stings, Treatment of, 307. 
Stomach, Structure of, 46. 

Digestion in, 49. 
Strychnine poisoning, 315. 
Sugar, 16, 28, 153. 

Absorption of, 61. 
Sulphuric acid poisoning, 314. 
Sunstroke, 312. 
Suppleness, Exercises for, 325. 
Swallowing, 46. 

Center of, 191, 203. 



Sweat, 163. 

glands, 157, 163, 169. 
Sweating as a heat regulator, 

168. 
Swimming, 330. 

Taking cold, 117, 169. 
Tallow, 17. 
Tapeworm, 239. 
Tarsal bones, 125, 152. 
Taste, 214, 226. 
' buds, 227. 

Confusion of, with smell, 
228 

Duration of, 228. 
Tastes, Different kinds of, 227. 
Tea, 26. 

Tear glands, 215. 
Teeth, 37, 38. 

Care of the, 39. 

Growth of, 38. 

Milk, 38. 

Permanent, 38. 
Temperature of body, 13, 167. 

Regulation of, 165, 168. 

Sense of, 233. 
Tendon, 137, 141. 
Tennis, 330. 
Tetanus, 271. 
Thinking, Location of, in brain, 

207. 
Thirst, 68, 231. 
Thorax, 109. 
Throat, 44. 

Sore, 46. 
Tibia, 125, 134, 152. 
Tinfoil poisoning, 314. 
Tissues, 88. 
Tobacco, 86, 182. 

Use of, 182. 
Toe nails, 161. 
Tone, 302, 312. 
Tongue, 37, 44, 226. 
Tonsilitis, 41, 259. 
Tonsils, 40, 44. 
Toothache, 305. 
Touch, Sense of, 213, 231. 
Trachea, 45, 106, 107. 
Trachoma, 275. 
Trichina, 239. 



INDEX 



349 



Tuberculosis, or consumption, 

20, 117, 277. 
Tubules of kidney, 156. 
Tympanic cavity, 223. 

membrane, 223. 
Typhoid fever, 20, 240, 260, 293. 

Ulna, 125, 152. 
Urea, 154. 
Ureter, 156. 
Uvula, 37. 

Vaccination, 241. 
Vaso-motor nerves, 99. 

Center of, 191. 
Vegetables, 23. 
Veins, 83, 88. 
Venous blood, 115. 
Ventilation, 116, 118, 295. 
Ventricles, 83. 
Vermiform appendix, 47. 
Vertebrae, 126. 
Vertebrates, 126. 
Villi, 59. 

Duties of, 61. 

Structure of, 60. 
Vocal cords, 106. 
Vomiting, 47, 313. 

Waist Muscles, Exercises for, 
328. 



Walking, Correct method of, 

324. 
Warm-blooded animals, 166. 
Warmth, Feeling of, 99, 233. 
Warts, 159. 

Waste products, 54, 63, 153. 
Water, 24, 25. 

Absorption of, 61. 

Filtering of, 295. 

Impurities in, 25, 293, 295. 

Inspection of, 293. 

Loss of, through lungs, 
114. 

of lakes, 25. 

of reservoirs, 25. 

of rivers, 26, 243. 

of springs, 25. 

of wells, 25. 
Water Commissioners, 292. 
Wheat, 21, 22. 
Whisky, 30. 
Whooping cough, 240, 274, 

. 300. 
Windpipe, 44, 45, 106. 
Wounds, Treatment of, 271. 
Wrists, Exercises for, 328. 

Yawning, Significance of, 319. 

Yeast, 27, 78. 

YeUow fever, 241, 265. 



10. 



SE P 8© l»G 



One copy del. to Cat. Div. 



29 *K) 



